Zoology Unit 2

Life cycle: human liver flukes

1. Eggs are shed into water with feces, each containing a complete miracidium. 2. Miracidium hatches after being eaten by a snail. 3. After being eaten by snail, turns into a sporocysts, then into a rediae. 4. Rediae turns into a cercaria that escape into the water until they encounter a fish. 5. Turn into a metacercarial cysts in the fish muscle. 6. Mammal eats raw/undercooked fish, metacercarical cysts dissolves in intestine, fluke lives 15-20 years.

Describe features, morphological and developmental, that would likely be found in the earliest ancestral mollusk.

1. Features characteristics of protostomes such as spiral cleavage and trochophore larva. 2. coelom

The climate of southeastern US and southeastern China are similar. Describe two separate factors that serve to keep flatworm parasites less common in the US than in China.

1. Less consumption of raw meat which means less cyst ingestion 2. More sanitation practices that prevent feces with eggs coming into contact with the snail intermediate host

Discuss two competing hypotheses for the origin of the body cavity. How does Lobatocerebrum inform this debate?

1. Libby Hymen's view: Flatworms are the first ancestor and first protostomes formed by schizocoely, which is where a coelom forms when a solid band of mesoderm surround the gut splits open, forming a space where fluid collects. 2. Enterocoely: The dueterstome way that is homologous back to the cnidarians. The body cavity was formed as an endoderm lining the gut pushes outward, enclosing a coelomic cavity. Lobatocerebrum is an example of the way a body cavity can compress, it goes with enteroceal, agains Libby Hymen's idea and is also a good example of progenesis.

Discuss developmental similarities between protostomes coelomates.

1. blastopore (1st hole) becomes mouth, anus forms second 2. spiral cleavage 3. coelom created by splitting 4. Mosaic embry 5. No identical twins

Describe the annelid body plan, including body wall, segments, coelom and its compartments, and coelomic lining. Explain how the hydrostatic skeleton of annelids helps them to burrow. How is the efficiency for burrowing increased by segmentation?

2 part head composed of prostomium and peristomium followed bysegmented body and a terminal portion called pygidium. head and pygidium are not segments. new segments develop right in front of pygidium with the oldest segments at the anterior end and the newest posterior. each segment contains circulatory, respiratory, nervous and excretory structs as well as a coelom. pair of coelomic compartments in each segment. coelomic lining made up of peritoneum that lines the body wall of each compartment which forms dorsal and ventral mesentaries that cover all organs. the body walls surround the peritoneum and coelom contains circluar and long. muscles. Burrowing efficiency is increased by metamerism because a segmented body allows for peristaltic contractions to occur.

What is meant by mesoderm from the 4D cell? Which phyla express this pattern? What is meant by a mulluscan or annelid cross at the 64 cell stage? Which phyla express which pattern?

4D cell is one cell at the 64 cell stage of development. They are usually cells around the lip of the blastual; used to create all of the mesoderm. Exhibited by lophotrochozoan protostomes. The cross is basically an engraving on the ball of cells that are in either an x or + shape. Molluscs and sipunculids = molluscan cross Annelids and echiurins = annelid cross First clue to evolutionary relationships

What is a lophophore? Are lopohphorates protostomes or deuterostomes? Discuss the characteristics that support your position and why characteristics that do not support your position are not important. What are some protostome characters found among lophophorates? What are their deuterostome characters?

A crown of ciliated tentacles surrounding the mouth but not the anus and containing an extention of mesocoel. - Functions as both a respiratory and feeding structure found in ectoprocta, brachipopoda, and phoronida. - Protostomes Deuterostome: DO NOT SUPPORT some show radial cleavage, coelom formed by enterogoely, coelom divided into 3 parts. Not important because most of the protostome characters come from ribosomal RNA and molecular data. The fact that ecto, brachi, and phoronids are currenty placed as protostome reflect acceptance of their molecular data in the face of conflicting and inconsisten morphological data. Protstome: DO SUPPORT; embryos typically exhibiting spiral mosaic cleavage, embryonic blastopores become the mouth, not the anus, coelom formed by schizocoely, which is where a coelom forms when a solid band of mesoderm surrounding the gut splits open, forming a space where fluid collects.

Dirofilaria

A genus of filarial worms including the heartworm and other species, usually found in mammals other than humans.

What are some adaptive advantages of a pseudocoel compared to the acoelomate condition? Explain the difference between a true coelom and a pseudocoel.

Acoelomates do not have a coelom. Psuedocoel. contain an internal cavity surrounding the gut but the vacity is not completely lined with mesoderm as it would be in a coelomate animal. A mesodermal layer occurs on the outer edge of the cavity but that layer does not for a mesentery. Some adaptive advantages are that the psue. shares some of the same functions as a coelom does, it gives space for development and differentiation of digestive, excretory,a nd reproductive systes a simple cirulation system of hydrostatic support. a true coelom is a body cavity comletely lined with mesodermal pertoneum.

Describe and trace the following lifecycles: mictic and amictic cycles of rotifers.

Amictic: Thin shelled rotifer eggs, may develop parthenogenetically into diploid (amictic) females. This happens the part of the year when environmental conditions are suitable. Life cycle= mitosis- amictic female- mitosis egg. If environmental conditions are bad, diploid mictic females will produce haploid eggs, which if not fertlized, will turn into haploid males. If fertilized, the haploid eggs are Mictic and develop a thick resistant shell and become dormant until environmental conditions are suitable again. Once it is a suitable condition they hatch into amictic females. Mictic Lifecycle: Egg- mitosis- amictic female- haploid egg- mictic female- meoisis- unfertilized egg- male- sperm- fertilization of egg- mitosis- egg- amictic female.

Which other invertebrate groups are likely to be the closest relatives of molluscs? What evidence supports and contradicts these relationships?

Annelids. They have a developmental pattern very similar to that of mollusks but the annelid body is metameric composed of serially repeated seguments where there are no true seguments in mollusks both annelids and mollusks are coelomate protostomes but the coelom is greatly reduced in mollusks as compared with annelids. there is much debate over this but possible mollusks with repeated body parts were derived from unsegumented molluscan ancestors.

eucoelomate

Any of the animals with "true" coelom, which is characterized by a body cavity completely lined with a peritoneum that attaches to organs

What is a pogonophora? Where does it live? What does it eat?

Beard worms. They live in mud on the ocean floor at depths of 100-10000m obtained only by dredging they livein long chitinous tubes in upright positions they have no mouth or digestive system, so they absorb some nutrients dissolved in seawater such as gllucose, amino acids, and fatthy acids. Most energy is derived from chemoautorophic bacteria that oxidize hydrogen disulfide to produce organic compounds from co2. the bacteria are helpd ina trophosome.

Cleavage: spiral, radial, bilateral

Bilateral: The first cleavage results in bisection of the zygote into left and right halves.

How do the valves of the brachiopods compare with the valves of bivalve molluscs?

Bivalves - Right and left valves hinged by ligament on dorsal surface. Umbo points towards anterior. Brachiopods - Pedicle valve (ventral) is larger, projecting beyond brachial valve (dorsal) at posterior

Briefly describe how a typical bivalve feeds and how it burrows.

Bivalves are filter feeders that depend on currents produced by cilia on their gills to gather food materials. bland cells on gills and labial palps secrete copious amounts of mucus which enlarges particles suspended in gill pores which slides towards food grooves at the lower edge of the gills. bivalves move by extending a muscular foot between valves pumping blood into a foot causeing it to sweel and act like an achor then contracting the foot to pull the animal forwards. they can burrow into mud sand wood or stone by using globular valves some ston borers valves have spines.

proglottid

Boxlike portion of a tapeworm containing a set of reproductive organs; usually corresponds to a segment

Describe adaptations in the circulatory and neurosensory systems of cephalopods that are particularly valuable for actively swimming, predaceous animals.

Circulatroy: closed system have accessory or brachial hearts at the base of each gill to increase the pressure of the blood going thorugh. this allows this to circulate enough water for their high oxygen requirements which is very valuable for actively swimming animals to get enough o2 in their muscles. neuro: most elaborate in mollusca largest brain which has giant nerve fiers which can initiate maximal conractions of mantle muscles for speedy escape. have high complex eyes excellent eye sight.

Describe the function of the clitellum and cocoon.

Clitelum are specific to oligochaeta and hirudinida. it is a reproductive structure in the epidermis that appears the worms exterior as a fat band around the middle. produces the coocon in which eggs are depsoitied during sexual reproduction.

What characteristics of phylum Cnidaria are most important in distinguishing it from other phyla? What type of larval form do they have?

Cnidocytes - Modified interstitial cells that hold the nematocysts (stinger) Radial polyp form Planula larva - free swimming, ciliated flat oval that is diploblastic Mouth surrounded by solid tentacles

Discuss the evolution of bivalve gills. Compare bivalve gills with the gills of other molluscs. Include a description of protobranch and lamellibranch gills along with a discussion of morphology, primary, and secondary functions.

Derived from primitive ctenidia by a great lengthening of filaments along each side of the central mass. Gills have water pores and channels. General bivalves have a lamellibranch gill that is used for both respiration and feeding, which fills the mantle cavity and has a mucous covering that catches particles that are then eaten by the bivavle. Protobranchs have been pushed to deep sea regions because they are out competed as their gills are only used for respiration.

What is an entoproct? What is an endoproct? How do the two differ?

Ento: Inside anus, tiny sessile resemble hydroid cnidarians but have ciliated tentacles that tend to roll inward. solitary or colonial all stalked well developed nerve ganglion. Ecto: outside anus, aquatic animals encrust hard surfaces. Sessile colony builders. Have zooids that for zoecium. Have ciliates that generate a current. Has lophophore digestive tract muscles and nerve centers. has zooid larva that metamorphozises into ancestrula before growing into a colony. when producing asexually the produce resistant hard capsules containing a mass of germinative cells. survive through winter and give rise to new ploypides in the spring.

Sense organs in modern trematodes and cestodes are poorly developed. Likewise other features appear simpler than what is thought to be their ancestor stock (turbellarian flatworms). Typically we think of evolution as leading to increases in complexity, however, it often seems that in parasitic groups simplicity in morphology is selected over complexity. Discuss why this might be the case. Use the beef tapeworm as a model in your discussion. The beef tapeworm currently infests castle, a mammal of more recent evolution. Did tapeworms only evolve as parasites after their modern hosts appeared? If not, what were they doing before then?

Even though evolution goes from simple to more complex, there are also times where it goes from more complex to simple. By not building a complex structure, the animal can shunt that energy elsewhere. Organisms find better ways to use energy then give them too many structures they don't need. In evolutionary terms, what works the best with the least amount of energy, has an advantage over other more complex organisms. The beef tapeworm perhaps had the ability to infect other species in earlier times. However, since the cow has become more prevalent, the tapeworm no longer needed the genetic mechanisms to invade all of the other species, and instead, just focused on the cow.

Gastropods have diversified enormously. Illustrate this statement by describing variations in feeding habits found in gastropods.

Feeding habits are super divers, but all include use of some adaptation of radula. most are herbivours and rasp aprticles of algae from hard surfaces some abalones hold seaweed with their foot and break off pieces with radula. some are scavengers that live on dead decaying flesh and others are carnivores that tear their prey with radular teeth some feed on bivalves by drilling holes through shells with teeth.

Peristomium

Foremost true segment of an annelid; it bears the mouth

Most freshwater clams have a bivalved ___________ stage that attaches to the gills and lives as a parasite for a few weeks.

Glochidia

Describe the phylum Gnathostomulida. Why do zoologists not classify nemerteans and gnathostomulids with Platyhelminthes? Nemerteans possess a body cavity formed by schizocoely. What is this cavity and how is it different from the cavity in most coelomate animals?

Gnathostomulia are jaw worms. They are made unique by their complex jaw structure. They have ciliated epidermis with one cilium per epidermal cell. Simple. Acoelomate body. No circulatory system. Develops with spiral cleavage, hermaphorodites. Not classified with platy because of their jaw. Nemerteans not classified bc they have a complete gut, outside anus and body cavity around proboscis.

Coral reefs are generally limited in geographic distribution to shallow marine waters. How do you explain this observation?

Hermatypic corals and their zooanthellae that make up coral reefs require warmth, light, and salinity of undiluted sweater. This limits them to very specific locations across the globe and keep them close to the surface due to water filtering the light.

Members of such a large and diverse phylum as Mollusca impact humans in many ways. Discuss this statement.

Humans can use mollusks as food, can obtain pears from the shells of bivalves and they can be pests because of damage they can cause (burrowing shipworms), snails and slugs can damage gardens and vegetation, and snails can serve as intermediate hosts for serious parasites of humans and animals.

Name and distinguish the taxonomic classes in phylum Cnidaria

Hydrozoa - Colonial jellies; velum in medusa; medusae produced by lateral budding Scyphozoa - Bell/cup jellies; strobilation - asexual reproduction via division of the body into segments Cubozoa - Box jellies; boxlike medusa; four evenly spaced tentacle clusters; complex, well developed eyes Anthozoa - Flower animals; no medusa stage; reproduce by budding; hexaradial

What functional problem results from torsion? How have gastropods evolved to avoid this problem?

In Gastropods, initially the veliger larval stage the mouth is the anterior and the anus is posteriour. Torsion is the process that changers the relative position of the shell, digestive tract, anus, nerves that lie alongside the digestive tract, and the mantle cavity containing the gills. The asymmetrical foot retractor muscle pulls the viscera organs and brings the anus from the posterior to the right side of the body. The digestive tract moves both laterally and dorsally so that the anus lies above the head. This switches the left gill, kidney, heart, and atrium to the right and vice versa. This allows the animal to draw its head inside the shell. The functional problem that results from torsion is called fouling, which is where there is the possibility of waste washing over the head and gills since the anus opens up over the head. Gastropods have evolved to avoid this problem by losing the gill, atrium on their right side due to carrying a coiled shell with a conispiral shape, leading to bilateral symetry. Though this was probably due to carrying a shell it also made it possible to avoid fouling because water is now brought into the left side of the mantle cavity not the right, carrying with it the waste. No organs on the right, so no harm no foul.

Compare the excretory system in each class of annelids

In each segment (metamere) of the organism, a pair of complete excretory structures called the metanephridium exists. The metanephridium has an extremity, the nephrostoma, which collects waste from the coelom, filtering it and causing reabsorption along its extension (similar to human nephron tubules). The material to be excreted goes out through a pore, the nephridiopore, which opens to the surface of the body.

Compare the circulatory system in each class of annelids

In organisms of the phylum Annelida, the circulatory system is closed, meaning that blood circulation takes place only within specialized vessels.

Labial palps

In some Mollusca, one of a pair of flap-like folds at the end of each tentacle by which food is transported to the mouth.

Nacreous layer

Innermost lustrous layer of a molluscan shell, secreted by mantle epithelium.

Name and give functions of the main cell types in the epidermis and in the gastrodermis of hydra. In what way is a hydra atypical as a hydrozoan?

Interstitial - undifferentiated stem cells found among the bases of the epithliomuscular cells. Gland - tall cells, located around the basal disc and mouth that secrete an adhesive substance for attachment and sometimes a gas bubble for floating. Sensory - found around the mouth and tentacles and on the basal disc; have a flagellum a sensory receptor Cnidocytes - 3 types: penetrants that penetrate and inject prey, volvents that recoil and entangle prey, and glutinants that secrete an adhesive substance used in locomotion and attachment Nerve - multiple axons form synapses with sensory cells, other nerve cells, epithliomuscular cells, and cnidocytes.

How do zooxanthellae contribute to the welfare of hermatypic corals?

It is a mutualistic relationship in which the zooxanthellae live in the coral tissues where they photosynthesize and fixate carbon dioxide which in turn furnishes food molecules for the coral. They also recycle phosphorus and nitrogen waste that would otherwise be lost, as well as enhance the corals' ability to deposit calcium carbonate.

Describe several features of the phylum Rotifera. What is a mastax with jaw-like trophy and a ciliated corona? Compare and contrast features of the phylum Gastroticha.

Live in freshwater lakes and ponds. Can be free living or colonial tolerant of environmental extremes ciliated coronas surround their head cilia on the coronoa beat in succession giving appearance of revolving wheel or pair of wheels they function in both locomotion and feeding have a foot bearing 1-4 toes and has both sessile and creeping forms mastax with jaw like trophy is the pharynx fitted with muscular portion equipped with hard jaws for sucking in and grinding food particles. They constantly chewing mastax is a distinguishing feature. Rotifers are diocious and produce eggs. protonephridia have flame cells.

How does a molluscan coelom develop embryologically? Why was the evolutionary development of a coelom important?

Mollluscs are lophorochozoan protostomes and develop via spiral mosaic cleavage and make a coelom by schizocoely which is where a coelom forms when a solid band of mesoderm surrounding the gut splits open forming a space where fluid collects this is important bc it tells if an organisms was a protostome or due.

Contrast the typical life cycle of a monogenean with that of a digenetic trematode

Monogenean- Direct with single host.. the egg hatches to produce ciliated larva which attach to host on skin or gills. Digenetic: indirect with multiple hosts. The first host is a mollusc and the definitive host is a vertebrate.

Compare and contrast the morphology of a Nautilus and a snail.

Nautilus * cephalopod * shell w/ gas chambers * siphon used for movement * closed circulatory system Snail * gastropod * shell houses internal organs * movement using foot * open circulatory system Both * coiled shell * simple eyes * tentacles * radula

Distinguish between opisthobranchs and pulmonates

Opi: sea hares, sea slugs, all marine partial or complete detorsion 2 pairs of tentacles can ursurp the photosynthetic machinery of their prey Plum: Land and freshwater no ctenidia mantle is a lung water=1 pair of antennae land =2

Diagram and discuss a cladogram showing a proposed phylogeny of the following taxa: Opisthobranchia, Nautiloidea, Monoplacophora, Prosobranchia, Bivalvia, Coleoidea, Pulmonata, Scaphopoda, and Polyplacophora. Make sure to include characters between each node.

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Diagram and explain the phylogeny of molluscan classes. Make sure to include a feature or two between each branch and node of the cladogram.

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The ______________ is the layer on the outside of the clam or mussel shell that provides protection from acidic water and may be colored to hide the clam in the mud.

Periostracum

Describe the layers of a mollusk shell.

Periostracum: outer organic layer made of ocnchiolin helps protect underlying calcareous layers. Prismatic: Middle layer composed of densely packed calcium carbonate secreted by the glandular margin of the matle and increase in shell size occurs at the shell margin as the animal grows. Narcreous: inner layer that lies next to mantle and is screted continously by the matle surface so it increases in thickness produces iridscent mother of pearl.

Compare and contrast the features of the following phyla: Phrondia, Ectoprocta, and Brachiopoda.

Phrondia -small wormlike animals that secrete a leathery or chitinous tube in which it lies free but never leaves. they thrust out tentavles on the lophophore for feeding. cilia on the teh tentacles direct a water current towards the mouth have blood vessels but an open circulatory system no heart blood with hempglobin moecious and dioecious. cleavae is radial have larvae called actinotroch can be asexual. Ectoproct- outside anus, aquatic animals encrust hard surfaces. Sessile colony builders. Have zooids that for zoecium. Have ciliates that generate a current. Has lophophore digestive tract muscles and nerve centers. has zooid larva that metamorphozises into ancestrula before growing into a colony. when producing asexually the produce resistant hard capsules containing a mass of germinative cells. survive through winter and give rise to new ploypides in the spring. All have a lophophore

What do planarians (triclad flatworms) eat, and how do they digest it?

Planaria eat living or dead small animals that they suck up with their muscular mouths. Food passes from the mouth through the pharynx into the intestines where it is digested by the cells lining the intestines. Then its nutrients diffuse to the rest of the body.

Contrast the body structure and life cycle of a planarian and a tapeworm

Planarians; Life cycle reproduce sexually and asexually by fission. Asexually they can regenerate non parasitic. Body structure is free living with soft flattened bodies covered with ciliated epidermis secreting cells and rodlike bodies. Mouth on ventral survacej sometimes near the center of the body, no body cavity except intercellular lacunae inparenchyma. Protonephridian have flame cells and they have ocelli. Have on ventral pair of longitundinal nerve cords. Forms ladder like patters Tapeworm: Parasitic in digestive tract of all clases of vertebrates, development indirect with two or more hosts. Body structure- general form is tapelike with scolex with suckers or hooks body divided into series of proglottids no digestive organs body of adults is covered with nocilliated sycytial tegument.

Compare and contrast synapomorphies of the phylums Platyhelminthes and Gnathostomulida.

Platy: Flatworms, tripblastic, incomplete gut, asexual, monoecious, no respiratory or skeletal system ans excretory system has flame cells. Gnath: tiny sand grain sized, complex jaw structure acoelomate, no circulatory system rely on diffusion for everything. monociliated epidermal cells.

Distinguish between polyp and medusa forms

Poly attached to something; sessile; asexual repro Medusa is free swimming; actually looks like jelly fish; sexual repro

Describe each class of Mollusca.

Polyplacophora - "chitons" Scaphopoda - "tusk shells" Bivalvia - "clams, oysters, mussels" Gastropoda - "snails and slugs" Cephlopoda - "squids, octopus, cuttlefish"

Why is Taenia solium a more dangerous infection than Taenia saginata?

Pork tapeworm vs. Beef tapeworm Pork tapeworm (solium) if ingested can take root in pretty much any tissue including nervous tissue such as the brain or spinal cord Beef tapeworms (saginata) only attaches in the intestine

Protonephridia

Primitive osmoregulatory or excretory organ consisting of a tubule terminating internally with flame bulb or solenocyte; the unit of a flame bulb system

The anterior-most and posterior-most portions of the annelid body are the ___________ and _____________, respectively.

Prostomium; pygidium

Why is bilateral symmetry of adaptive value for actively motile animals?

Puts sense organs toward the front so they can better sense where they are going or if anything is coming toward them. Also important in equilibrium and balance.

What are the characteristics of the phylum Mollusca that distinguish it from other phyla?

Radula Muscular foot Mantle Cavity

Radula

Rasping tongue found in most molluscs

Give three differences between nemerteans and playhelminthes

Ribbon worms have a probscis; flat worms eversible pharynx Ribbon worms dioecious, flatworms monoecious Ribbon worms have a complete digestive system; flatworms do not.

Scyphomedusae

Scyphomedusae (phylum Cnidaria, class Scyphozoa) A subclass of medusoid; cnidarians whose members lack a velum and have a coelenteron partly divided by four interradial endodermal septa.

What characteristics of phylum Annelida distinguish it from other phyla?

Segmentation/ Metamerism Chaetae - bundles of chitonous hairs

Life cycle: Shistosomiasis- Blood Fluke

Shistosomiasis- Blood Fluke 1. Eggs discharged in human feces or urine, hatches in water. 2. Miracidium finds and penetrates host snail. 3. Sporocyst develops in snail host. 4. Cercaria released in water. 5. Penetrates skin of human host, adult schistosomes mate.

Compare cnidarians and ctenophores, give five ways in which they are similar and five ways in which they are different

Similar 1. Neither have a respiratory system or coelomic cavity 2. Both have statocysts to assist in balance and equilibrium 3. Extensible tentacles 4. Oral and aboral ends, but no definitive head 5. Extracellular digestion Different 1. Cnidarians have stinging cnidocytes for feeding while Ctenophores have colloblasts which are sticky cells used to capture prey. 2. Cnidarians can be marine or freshwater, while all ctenophores are marine 3. Cnidarians have an incomplete called a gastrovascular cavity, while ctenophores have a complete gut 4. Cnidarians have a nerve net, whereas ctenophores have a nervous system made up of a subepidermal plexus 5. Cnidarians have muscle contractions via epitheliomuscular cells, while ctenophores use muscle fibers

Compare and contrast synapomorphies of the phylums Echiura and Sipuncula.

Sip: benetic marine worms known as peanut worms, no segmentation or setae. easily recognized by the presence of an introvert proboscis which is continually run in and out of the anterior end. digestive tract forms a ushape no circulatory/respiratory system reproduces asexually but sexes can separate. Ech: found in all oceans, worms that burrow into the mud or sand. sausage shaped and cylindrical. flattened extensible proboscis cannot be retracted known as spoon worms large coelom closed circulatory system has trocophore stage.

Benthic marine worms with a tentacle introvert that develop by spiral cleavage with a molluscan cross are found in phylum ____________.

Sipuncula

What is an Acathocephalan? How do acanthocephalans get food?

Spiny headed worms characterized by a probscis bearing rows of recurved spines by which it attaches inself to the intestine of its host. all are endoparasitic living as adults in the intestine of vertebrates. they get food by absorbing all nutrients through their tegument by specific membrane transprot systems and pinocytosis. tegument also bears enzymes to help the worm absorb amino acids. they require host dietary carbohydrates, glucose diffuses down a concentration gradient into the worm

Describe how cephalopods swim and how they eat.

Swim by forecully expelling water from mantle cavity through a ventral funnle sort of like ject propulsion. The funnel is motile and can be pointed backwards or fowards for direction,t he force of water expulsion controls speed. they use tentacles to search for and grasp food eat through beak like mouths.

Compare the nervous system in each class of annelids

THe most primitive flatworm nervous system found in turbellarines is a subepridermal plexus like a nerve net in scnidarians. Other have addition to a nerve plexus 1-5 pairs of longitudinal nerve cords. Planarians have 1 ventral pair forming a ladder like pattern. They all have a pari of anterior ganglia with the longitudinal nerve cords.

Life cycle: beef tapeworm

Taenia Saginata 1. SHelled larvae in feces contaminates grass. 2. Cow eats contaminated grass 3. Cysts in cow muscle measly beef 4. Juviniles in cysts devlop into invaginated cysticerus 5. Undercooked meat with livng cystercus 6. cysticercus eaten by human in beef.

What is progenesis? How does this relate to the phylogeny of Platyhelminthes? How does this view compare to the planoid theory discussed by Libby Hymen?

The maturation of gametes in an organism that is still otherwise at the juvenile stage of development (see paedogenesis). Progenesis can lead to paedomorphosis. Progenesis relates to they phylogeny of platyhelminths because there are theories that the ancestor of Platyhelminthes were not aceolomate, like current flatworms are today, but were like a worm with a body cavity. The simplicity of the platy is a derived feature, not ancestral. This view compares to the planoid theory because she did not think flatworms were progenic, but had the idea that they were simple because they were ancestral. She thought platy formed the keystone group that sat between protostomes and deuterostomes, and that the ancestors of protostomes and deuterostomes were a worm with a body cavity. Evolving simplicity was not the case.

What is an unusual feature of the nervous system of Cnidarians?

They don't have a central nervous system, but rather a nerve net. Many of the synapses have vesicles of neurotransmitters on both sides, allowing transmission across the synapse in either direction. They also don't have any insulating material (myelin) on the axons.

Recent evidence suggests that members of Acoelomorpha constitute a sister group for all other Bilateria. How do members of this group differ from typical protostomes?

They have a duet spiral pattern of new cells during cleavage events after fetilization and lack a true brain, and have radial arrangememnt of nerves in the body instead of ladderlike pattern seen in platy. Aceolomorph statocysts differe in structure from thos of platy. Recently phylogenetic studies using moleuclar characters describe acol. as early diverging, bi laterally symmetrical tripoblasts with only 4-5 hox genes unlike platy.

Describe the phylum Cycliophora. How many species are described and when was the first species described? Where does it live? What does it eat? What is meant by a dwarf parasitic male?

Tiny. Only 3 species described and the first one 1995. They live on the mouth parts of marine decapod crustaceans in northern hemisphere. feed by collecting bacter or bits of food dropped from their lobster host on the ring compound cilia that surrounds the mouth. ALL females, males are basically tumorous masses on female that does nothing but produce sperm. Takes nutrientes from female, parasite on female.

Contrast asexual reproduction in triclad flatworms, trematodes, and cestodes

Triclad flatworms: Asexual reproduction of Flatworms Can reproduce asexually or sexually. Asexually they reproduce by fission. They have the ability to regenerate missing parts. Trematodes: Undergo asexual reproduction in their intermediate snail hosts. Miracidium enters the tissues and transforms into a sporcyst which produces one generation of redae which gives rise to the cercariae. These two asexual stages in the inermediate host allow a single miracidium to produce over 250,000 cercaria. Cestodes: Budd off hundreds of offspring. also known to cross fertilize and self fertilize. When raw or undercooked measly meat is eaten by a suitable host the cyst wall dissolves scolex attaches to the intestinal mucosa and proglottids begin to develop.

What is a trochophore? Draw and label a diagram of a trochophore including important morphology. Finally list and discuss the taxa that have a trochophore and taxa that have something that resembles a trochophore.

Trocophore is the larval stage of mollusk it is free swimming. found in mollusc and annelids taxa have something that resembles a trocophore occurs in tubellarians, nemertines, brach, phoronids, and echiurids.

Name and distinguish the taxonomic classes in phylum Playhelminthes

Turbellaria- "Free living flatworms" *Free living *Eversible pharynx Trematoda - "Flukes" *Anterior adhesive organ Cestoda - "Tapeworms" *Scolex *No digestive system

Describe three specific interactions of anemones with nonprey organisms

Zooxanthellae live within their tissues and the anemone profits from the products of algal photosynthesis. Attachment to hermit crabs. The crab gets it to attach for protection, then the anemone gets free transportation and food particles. Anemone fishes live within anemones due to some unknown property of their skin that keeps the nematocysts from discharging. Shelter for the fish, ventilation of the anemone and removing of sediment

Osphradium

a chemoreceptive sense organ in aquatic snails and bivalves that tests incoming water

Trochophore

a free swimming ciliated marine larva characteristic of most molluscs and certain ectoprocts, brachiopods, and marine worms

Tornaria

a free swimming larva of enteropneusts that rotates as it swims; resembles somewhat the bipinnaria larva of echinoderms

What is hirudin? What animals produce it? How are similar compounds used in medicine?

a gray or white, water-soluble acidic polypeptide obtained from the buccal gland of leeches, used in medicine chiefly as an anticoagulant. Used for safer anticoagulants to prevent clotting during and after surgeries.

sporocyst

a larval stage in the life cycle of flukes; it originates from a miracidium

typhlosole

a longitudinal fold projecting into the intestine in certain invertebrates such as the earthworm

Velum

a membrane eon the subumbrellar surface of jellyfish of class hydrozoa

miracidium

a minute ciliated larval stage in the life of flukes.

Setae

a needlike chitinous structure of the integument of annelids, arthropods and others

tapeworm

a parasitic flatworm, the adult of which lives in the intestine of humans and other vertebrates. It has a long ribbonlike body with many segments that can become independent, and a small head bearing hooks and suckers.

Trichina

a parasitic nematode worm of humans and other mammals, the adults of which live in the small intestine. The larvae form hard cysts in the muscles, where they remain until eaten by the next host.

Metameres

a repeated body unit along the longitudinal axis of an animal

parenchyma

a spongy mass of vacuolated mesenchyme cells filling spaces between viscera, muscles, or epithelia

Strobila

a stage in the development of the scyphozoan jellyfish

Torsion

a twisting phenomenon in gastropod development that alters the position of the visceral and pallial organs by 180 degrees.

Metanephridia

a type of tubular nephridium with the inner open end draining the coelom and the outer open end discharging to the exterior

Since flatworms and ribbon worms lack a coelom or a pseudocoel, they are termed _________ animals

acoelomate

The ciliated planktotophic larva of phronids is called a/an __________ larva.

actinotrocha

Cephalopod

an active predatory mollusk of the large class Cephalopoda, such as an octopus or squid.

scolex

an attachment organ or holdfast of a tapeworm; bears suckers and in some hooks and posterior to it new proglottids are differentiated.

polychaetes

any marine annelid worm of the class Polychaeta, having a distinct head and paired fleshy appendages (parapodia) that bear bristles (chaetae or setae) and are used in swimming: includes the lugworms, ragworms, and sea mice

liver fluke

any of various trematode worms that invade the mammalian liver; especially : one of the genus Fasciola (F. hepatica) that is a major parasite of the liver, bile ducts, and gallbladder of cattle and sheep, causes fascioliasis in humans, and uses snails of the genus Lymnaea as an intermediate host

Pedal laceration

asexual reproduction in sea anemone, a form of fission

Statoblasts

asexually produced overwintering stage of many freshwater extoprocts

Pogonophorans use symbiotic chemoautotrophic bacteria located in the _______________.

bacteriocytes

Hexacorallia

belong to the order Scleractinia; called true or stony corals; miniature sea anemones that live in calcareous cups that they have secreted; gastrovascular cavity divided by septa in multiples of 6; tentacles surrounding mouth, but lacks a siphonoglyph; limy skeletal cup instead of a pedal disc

Bilateria

bilaterally symmetrical animals

Glochidia

bivalved larval stage of freshwater mussels.

Glochidium

bivalved larval stage of freshwater mussels.

columella

central pillar in gastropod shells

rhinophore

chemoreceptive tentacles in some molluscs.

Polyplacophora

chitons all of which have the foot occupying the whole ventral surface of the body and the shell composed of eight calcified dorsal plates

Siphonoglyph

ciliated furrow in the gullet of sea anemones

Nephrostome

ciliated, funnel shaped opening of a nephridium

Describe three ways that various polychaetes obtain food.

clamworms- seize food with jaws wich proturde through the mouth with they evert their pharynx food is swallowed as worm width draws pharynx. movememnt of food happens through perstalsis. Tube worms: particle feeders use cilia or mucus to obtain food. Use radioles or feather tentacle arms to capture food in grooves and bring it down to the mouth. Pogonophorans: absorb nutrients dissolved in the water because they have no mouth or digestive tract

When earthworms mate, the __________________ secretes mucus to hold them together.

clitellum

Fringing reefs

close to a landmass with either no lagoon or a narrow lagoon between reef and shore

Ctenidia

comblike structures, especially gills of molluscs

Eutely

condition of a body composed of a constant number of cells or nuclei in all adult members of a species, as in rotifers, acanthocephalans, and nematodes

Fouling

contamination of feeding or respiratory areas of an organism by excrement, sediment, or other matter.

What are some protostome characters found among lophophorates? What are their deuterostome characters?

deuterostome: i) tripartite body plan (prosome, mesosome, metasome), each with separate, paired coelomic compartments developmentally, ii) radial cleavage protostome: i) blastopore = mouth in Phoronida, ii) protonephridia in some larval forms, iii) chemistry of exoskeleton (chitin based)

Scaphopoda

distinctive group of molluscs commonly known as the "tusk shells" because their shells are conical and slightly curved to the dorsal side, making the shells look like tiny tusks

Bilateral asymmetry

divided into mirrored right and left halves

Radioles

featherlike processes from the head of many tubicolous polychaete worms used primarily for feeding

Pedalium

flattened blade at the base of the tentacles in cubozoan medusa

Hermaphroditic

have both male and female functional reproductive organs

Planospiral

having the shell coiled in one plane —used especially of foraminifers and gastropod mollusks

If an individual turbellarian contains organs of both sexes, it is termed ___________.

hermaphroditic

The main structures that taste food and direct it into the mouth of a clam are the _____________.

labial palps

Veliger

larval form of certain molluscs; develops from the trochophore and has the beginning of a foot, mantle, and shell

monoplacophora

meaning "bearing one plate", is a polyphyletic superclass of molluscs with a cap-like shell now living at the bottom of the deep sea.

The packing tissue that make acoelomate flatworms "solid" is ________.

mesoderm

Circular muscles

muscle layer encircling the body between the epidermis and longitudinal muscle layer

Turbellarians have light-sensitive organs called ___________.

ocelli

Octocorallia

octomerous symmetry with eight pinnate tentacles and eight unpaired, complete septa; all colonial and have gastrodermal tubes called solenia

Rhopalium

one of the marginal, club -shaped sense organs of certain jellyfishes

Parapodium

one of the paired lateral processes on each side of most segments in polychaete annelids

Nephridia

one of the segmentally arranged, paired excretory tubules of many invertebrates, notably the annelids.

Solenogastres

one subclass of small, worm-like, shell-less molluscs (Aplacophora)

diploblastic

organism with two germ layers - endoderm and ectoderm

periostracum

outer layer of a molluscan shell

Paired appendages used for locomotion in polychaetes are called ____________. The dorsal portion of this structure is called the ______________ while the ventral portion is called the ______________.

parapodia; notopodia; neuropodia

Longitudinal muscles

pertaining to or extending along the long axis of the body, or the direction from front to back, or head to tail.

Kinorhyncha

phylum of small (1 mm or less) marine invertebrates that are widespread in mud or sand at all depths as part of the meiobenthos. They are also called mud dragons.

Ectoprocts have a __________ larva that metamorphosizes into an ________ before growing into a colony.

planula; polyp

Seminal receptacle

pocket related to the semen of an earthworm

opisthaptor

posterior attachment organ of a monogenetic trematode

Pygidium

posterior closure of a segmented animal, bearing the anus

How are members of clade Clitella distinguished from polychaetes?

presence of a Clitellum

Operculum

protective plate in some snails

The tonguelike, rasping organ in the head of many molluscs is the _____________.

radula

Atolls

reefs that encircle a lagoon but not an island; typically slope rather steeply into deep water at their seaward edge

Ephyra

refers to castlelike appearance. Medusa bud from a scyphozoan polp

Prostomium

region of a segmented animal anterior to the mouth

Gonangium

reproductive zooid of a hydroid colony

Hydrorhiza

rootlike stolon that attaches a hydroid to its substrate

Barrier reefs

runs roughly parallel to shore and has a wider and deeper lagoon than does a fringing reef.

Molluscs with a tubular shell, open at both ends are the class ________________.

scaphopoda

The head region of a tapeworm is called the __________.

scolex

Statocyst

sense organ of equilibrium, a fluid-filled cellular cyst containing one or more granules used to sense direction of gravity.

Perisarc

sheath covering the stalks and branches of a hydroid

Velarium

shelflike extension of the subumbrellar edge in cubozoans

Seminal vesicle

small hollow organs that carry the semen of an earthworm

mantle

soft extension of the body wall in certain invertebrates, for example, brachiopods and molluscs, which usually secretes a shell

Patch reefs

some distance back from the steep, seaward slop in lagoons of barrier reefs or atolls.

flame cells

specialized hollow excretory or osmoregulatory structure of one or several small cells containing a tuft of flagella and situated at the end of a minute tubule; connected tubules ultimately open to the outside

The flatworms typically have __________ cleavage.

spiral

Hydrocaulus

stalks or stems of a hydroid colony, the parts between the hydrorhiza and the hydranths.

Asexual resistant bodies of freshwater ectoprocts are called __________.

statoblasts

cercaria

tadpolelike larva of trematodes (flukes)

triploblastic

the embryo has three primary germ layers- ectoderm, mesoderm, and endoderm

Cephalization

the evolutionary process by which sensory organs and specialized appendages become localized in the head end of animals.

shell

the hard protective outer case of a mollusk or crustacean

Coenosarcs

the inner, living part of hydrocauli in hydroids

Hydromedusae

the medusoid phase of a hydroid coelenterate

Prismatic layer

the middle layer of the shell of a mollusk, consisting of calcite or aragonite.

Pneumostome

the opening of the mantle cavity of pulmonate gastropods to the outside.

Schphistoma

the poly form of a scyphozoan

Gills

the respiratory organ by which oxygen is extracted from water flowing over surfaces within or attached to the walls of the pharynx.

What is the function of the siphuncle in cephalopods?

the siphuncle connects the shell chambers of a gastropod its living. its purpose is to creat a high local osmotic pressure so water is drawn out of the cell chambers by osmosis this allows the shell to be at really deep pressures without inloding.

Briefly describe the habitat and habits of a typical chiton.

their habitats are rocks and their plates overlap posterior and are dull colored in order to blend in. they prefer rocky surfaces in interidal regions although some live at great depths most are stay at home organisms that stray only short distances for feeding feed by scraping algae off rocks or uses specialized head flat. if detached fromrock it can roll up like armadillo for protection has most gills, osphradia, have heart andkidnes. sexes are seperate no veliger stage trocophore only.

Acontia threads

threadlike structures bearing nematocysts located on mesentery of sea anemone.

Odontophore

tooth-bearing organ in molluscs, including the radula

Because they have three germ layers, flatworms and ribbon worms are ___________.

triploblastic

Septal filaments

unattached edge of an internal partition in a sea anemone gastrovascular cavity that extends into the cavity and is armed with nematocysts and gland cells

Primary septa/ Mesenteries

walls between two cavities with the gastrovascular cavity

acoelomate

without a coelom, as in flatworms and proboscis worms