Lab Practical 2: Survey of the Animal Kingdom Phylum Mollusca and Annelida

List phyla and their body plans.

-Acoelomate: Platyhelminthes -pseudocoelomate: Nematodes -coelomates: Mollusks, and Annelids:

List several functions of parapodia and setae.

-Movement -Respiration -Defense against prey (filled with poison) -Filter food out of the water

external anatomy of earthworms (class oligochaeta)

-prostomium: fleshy lobe that proceeds mouth -peristomium: first body segment posterior to mouth -clitellum: most obvious external feature, series of swollen segments at anterior third of body, where copulating worms attach and exchange sperm, copulating worms are hermaphroditic (produce egg and sperm cells) -sperm mature in seminal vesicles and exit worm through male gonopores on segment 15 -sperm then move to adjacent worm to openings of seminal receptacles -worms separate after copulation -clitellum picks up eggs from female gonopores and stored sperm from seminal receptacles a few days later -once fertilized in mucous band, worm releases it as cocoon

Mollusks exhibit a variety of feeding methods. List at least four and discuss adaptations and examples for each type.

1) herbivorous and use radula to scrape off food, adaptation when radula has venom 2) predation by cephalopods 3) capture food with tentacles 4) filter feeding gills

How many segments of an earthworm have a heart?

5

How many setae are on each segment of the earthworm? Are they paired?

8, yes

How do the layers of musculature in an earthworm differ from those of a nematode?

Annelids have circular as well as longitudinal muscles

How could absorption in the intestine be increased without increasing the intestine's length?

Increase the surface area, such as a typhlosole

What features of Nereis (polychaete) indicate that it is an annelid?

It lives in a marine habitat. It uses seta and parapodia for locomotion. It also falls into the Annelid category because it is a worm and has no appendages

The common name of the sea mouse refers to what external feature characteristic of polychaetes?

It refers to the external feature of their body (skin). This is because the body is covered in chaetae (hairs)

What is the difference in general body shape of leeches compared to oligochaetes or polychaetes?

Leeches are flat while oligochaetes and polychaetes are cylindrical

Is internal segmentation of a leech as distinct as that of an oligochaete?

No, internal segmentation of a leech is greatly reduced

List two or three features of an earthworm cross section that distinguish the dorsal and ventral surfaces.

Position of the nerve cord, position of pairs of setae and nephridia

A snail shell is quite different from the familiar bony skeleton of a mammal. In what ways does a shell function as a skeleton?

Protection, Support, Sensing, Defense, provide a frame work for attachment of musculature, feeding, similar to mammalian skeleton

Reproductive, body cavity surrounded by mesoderm, and digestive system

Reproductive, body cavity surrounded by mesoderm, and digestive system

Find the mouth at the base of the tentacles. What is the shape and consistency of the jaws?

beak shape

You have examined at least three phyla commonly referred to as "worms" How would you define this term?

bilateral, cylindrical, soft-bodies, tapering ends, mobile

Phylum Mollusca: Class Polyplacophora

chitons, exclusively marine, eight shell plates and all four structures

What muscles allow the worm to change its length and thickness?

contraction of circular muscles decreases thickness and lengthens body while contraction of longitudinal muscles increases thickness and shortens body -earthworms use hydrostatic pressure to achieve locomotion, bristles help prevent back sliding

How does an earthworm's motion differ from that of a snake and nematode?

earthworms motion is more shortening and lengthening while snakes and nematodes are more undulatory

Phylum Annelida (7)

earthworms, bristleworms, leeches -many segmented coelomates -repetition of body units (metamerism) -well developed closed circulatory system -2 clades: Errantia and Sedentaria -complete digestive tract -bristles (setae) on each segment that anchor them during crawling -3 classes: Polychaeta, Oligochaeta, Hirudinea

Cephalopods are considered by many to be the most distinctive class of mollusks. What makes them seem almost out of place?

eyes allow for much better movement and seeing

What features of squid and octopuses are adaptations for predation?

eyes, grasping tentacles, tough jaws

Of what economic importance are earthworms?

important for plant growth

Phylum Annelida: Class Hirudinea (8)

include leeches, primarily freshwater ectoparasites -not segmented as distinctly -lack setae -dorsoventrally flattened -anterior and posterior suckers that hold prey -hermaphroditic -species with copulatory organs inject a packet of sperm (spermatophore) into female gonopore -species without copulatory organs copulate by injecting spermatophore directly through epidermis of partner, cells move to ovaries to fertilize -cocoon in 2-months after

What function other than feeding do suckers serve?

locomotion

Some land snails have formed a lung like structure from a major layer of tissue. What is that layer?

mantle

Phylum Annelida: Class Polychaeta (3)

marine worms living in sediment -parapodia appendages on each segment -these appendages have a large surface area, are highly vascularized with blood vessels, and help the polychaete move and respire -many setae on parapodia that are filled with poison or help filter food

Phylum Annelida: Class Oligochaete (2)

movement involves extension, anchoring, and contraction that occur by alternating contractions of circular and longitudinal muscles -contractions pull against a hydrostatic (water pressure) support system rather than against a rigid skeleton -lack parapodia and have few setae

Are setae visible on a leech?

no

Is immobility a problem for filter feeders such as oysters? Why or why not?

no, a moving water column is often accessible, or cilia on the body of a filter-feeder will move water and trap food particles

Does the earthworm move randomly?

no, moves towards damp and avoids light

What features of Lumbricus indicate that it is an annelid?

segmentation and bristles (setae)

Phylum Mollusca: Class Gastropoda (2)

snails and slugs, undergo torsion as embryos which folds gut so that anus is bent back over head -single coiled shell on many -most are marine

Phylum Mollusca (7)

snails, clams, octopuses, squids, nudibranchs -soft bodied coelomates with several unique structures -shells: made of calcium carbonate -mantle: tissue that secretes shell, present in all but doesn't work in slugs -radula: a rasping tongue, present in most, peels off strips of material -foot: muscular structure for grasping substrate and movement -4 classes: Polyplacophora, Bivalvia, Gastropoda, Cephalopoda -open circulatory system except cephalopods

What is the texture of the mantle of Anodonta (clam)?

soft and fleshy

Phylum Mollusca: Class Cephalopoda (6)

squids, octopuses, cuttlefishes, nautiluses -shell reduced in squids and octopuses to an internal rod -spiral gas filled shell in nautiluses, allows it to change buoyancies and resist water pressure -predatory carnivores use 8 or more arms to grasp prey -highly intelligent -closed circulatory system -food modified into tentacles

Why are sensory organs more prominent in cephalopods than in other classes of mollusks?

they are important because cephalopods are both prey and predators

In what ways are image forming eyes significant to fundamental processes for cephalopods?

this allows them to be aware of the predators and prey around them

How could predators attack an animal closed "tight as a clam?"

through the shell or apply great pressure to open the shell

What are some functions of suckers in squid?

to attach to the host or substrate

Phylum Mollusca: Class Bivalvia (5)

two shelled clams, scallops, mussels -no radula, filter feed using ciliated gills -dorsally hinged shell in two parts -mantles of left and right valves join posteriorly to form a ventral incurrent siphon and a dorsal excurrent siphon that direct water through the clam -mantle cavity is space between mantle and visceral mass -cilia moves food to labial palps that direct food to mouth

Does the ventral nerve cord traverse the entire length of the body?

yes

Is the inside of the digestive tract the same from the pharynx to the end of the intestine? Explain.

no, there is specialization as crop stomach, etc

Are siphons in Odonata as obvious as they are in figure 38.8?

no, they are formed by union of the mantle on each side of the shell

internal anatomy of earthworms

-muscular pharynx: suction and ingestion of food -esophagus: transport of food -crop: food storage and some digestion -intestine: absorption of nutrients -rudimentary (basic form) brain anterior and dorsal to pharynx and continuous with ventral nerve cord -paired nephridia: occur in each segment, small, white, convoluted tubes, inner surface of each segment, function like kidneys by collecting and releasing excretory waste -nephrostomes: ciliated, funnel shaped and on ends of nephridia, gather waste products that are released from nephridiopores (external pores) -dorsal blood vessel and ventral blood vessel: main vessels, connected by five lateral "hearts" -typhlosole: internal fold of tissue arising from dorsal wall, creates U shaped intestinal lumen and doubles surface area for absorption

How could production of a packet like spermatophore contribute to the evolutionary success of leeches in their environment?

The spermatophore would protect the eggs from the environment, therefore ensuring their survival to adulthood and breeding

What is the probable function of the tentacles shown in figure 38.9b?

They are probably used to capture food, and to protect themselves against predation

Are parapodia significant to fundamental processes for polychaetes? In what ways?

They are used for locomotion. This means that yes, they are important because they help them swim, and serve for respiration at the same time

Earthworms have no lungs or gills. Do they "breathe" if not how do they obtain oxygen to survive?

They breathe through their skin. Air dissolves on the mucus of their skin, so they MUST stay moist to breathe. If worms dry out, they suffocate. As fresh air is taken in through the skin, oxygen is drawn into the worm's circulatory system, and the worm's hearts pump the oxygenated blood to the head area.

How does the foot of a bivalve differ from that of snails or chitons?

the muscular foot of a snail is broad and flat to meet flat surface while the muscular foot of a clam is tapred to penetrate sediment

In what ways would having a shell contribute to the survival and reproductive success of mollusks in their environment?

the shell can be used to protect the soft body of the organism from predators

Do you suppose bloodletting by leeches was a good technique to cure psychosomatic illnesses? Why or why not?

yes, more efficient and less damaging than hypodermic suction

Do all of the tentacles of a squid have suckers?

yes, the only difference is that the sessile arms have them on their inner surface and the larger tentacles have them only on the larger areas at the ends