Lab 7 Nematoda - EVERYTHING

Nematoda General Information

"Roundworms" Diversity not easily appreciated as most look the same Second most diverse animal phyla at the species level - 2% of species described - Likely 1 million species Have adapted to nearly every environment - Terrestrial, freshwater, marine - Tropical, polar, arid, alpine, subterranean Make up ~80% of all individual animals Most are free-living, but some are parasites - Example: Dog/cat Heartworm Huge economic and medical relevance Caenorhabditis elegans (C. elegans) is an important model organism for developmental studies Most are very small but largest species is a sperm whale placental parasite Placentonema gigantissima

What is the difference between male and female nematodes?

1. Males are smaller 2. Males have a hooked "tail" with a spicule

CIRCULATION:Describe the circulatory system (e.g. diffusion, open system, etc.). A)Diffusion B)Open circulatory system C)Closed circulatory system D)3-chamber heart E)4-Chamber heart

A)Diffusion

RESPIRATION:Describe how the group respires (e.g. diffusion, book lungs, gills, etc.). A)Diffusion B)Book lungs C) Lungs D)Gills inside mantle E)Gils outside the mantle F)Vascularized tissue lining the mantle cavity

A)Diffusion

SKELETON/SUPPORT:List the structures or ways this group of animals support themselves (e.g. hydrostatic skeleton, exoskeleton, etc.). A)Hydrostatic skeleton B)Endoskeleton C)Exoskeleton- like a cuticle

A)Hydrostatic skeleton C)Exoskeleton- like a cuticle They're ecdysozoans with an outer cuticle

REPRODUCTION:Describe the types of reproduction that occur in the group (e.g. sexual vs. asexual) and any other characteristics or specializations they may have for reproducing (e.g. monoecious vs. dioecious, fission, budding, etc.). A)Sexual B)Monoecious ONLY C)Dioecious ONLY D) Both monoecious and dioecious E) Some alternation of sexual and asexual stage F)Asexual reproduction

A)Sexual D) Both monoecious and dioecious

DIGESTION/FEEDING:Describe the digestive process (e.g. incomplete and extracellular) and any specializations for feeding (e.g. cnidocytes, tentacles, etc.). A) Incomplete gut / gastrovascular cavity B) Complete (mount and anus) C)Triradiate lips D) Free living E) All of the above F) Only C G) B, C and D

B) Complete (mount and anus) C)Triradiate lips D) Free living

ORGANIZATION:At what level is the basic body plan organized? (e.g. cell, tissue, organ, etc.) A)Tissue level B) Organ level C)none of the above

B) Organ level

EXCRETORY/OSMOREGULATION:List how the group eliminates waste from their systems (e.g. diffusion, nephridia, Renette cells, Malpighian tubules etc.). A)Diffusion B)Nephridia C)Malpighian tubules D)Kidneys

B)Nephridia

EMBRYONIC DEVELOPMENT:List the characteristics found during the formation of the blastula (e.g. triploblastic, deuterostome, etc.). A) Diploblast B)Triploblast C)Protostome D)Deuterostome E)Acoelomate F)Pseudocoelomate G)Eucoelomate (o coelomate) H)No embryonic development

B)Triploblast C)Protostome F)Pseudocoelomate

Ancestral State of Nematoda

Being free-living (not parasitic) seems to be the ancestral state for nematodes - Parasitism of plants and animals has arisen at least 15 times independently in this group - Some extant nematode species also display lifestyles that are proposed to be on the evolutionary trajectory to parasitism

SENSORY/NERVOUS:Describe the nervous system (i.e. ganglia, CNS, ventral nerve cord, etc.) and any sensory specializations found in the group (e.g. auricles, eyes, antennae, etc.). A)Nerve net B)Ocelli C)Cerebral ganglia D)Ventral nerve cord E)Dorsal nerve cord F)Cephalization

C)Cerebral ganglia D)Ventral nerve cord E)Dorsal nerve cord F)Cephalization

MOVEMENT/LOCOMOTION:What structures are used to help them move around their environment?(e.g. types of muscles, jointed legs, cilia, etc.). A)Cilia B)Glides using muscles C)Longitudinal muscles only D)Circular muscles only E)Both longitudinal and circular muscles F)Uses flagella to move G)Hydrostatic skeleton

C)Longitudinal muscles only G)Hydrostatic skeleton

CLASSIFICATION: Only answer the phyla, classes, subclasses and other classification that you are responsible for knowing this week for Lab 7 A)Phylum Annelida B)Phylum Mollusca C)Phylum Nematoda D)Platyhelminthes E)Cnidaria

C)Phylum Nematoda

Phylum Nematoda Digestion/Feeding

Complete gut No muscles around gut Triradiate lips

SYMMETRY:What type of symmetry is found in the basic body plan? (e.g. asymmetrical, radial. etc.) A)Asymmetry B)Radial symmetry C)Pentaradial symmetry D)Bilateral symmetry

D)Bilateral symmetry

Phylum Nematoda Leaf nematodes

Development of linear lesions between the leaf veins causing the leaf to become striped in appearance

Phylum Nematoda Reproduction

Dioecious Male smaller, hooked "tail" with spicule Cryptobiotic eggs- live for really long time, very resistant Free-living species and parasitic nematodes, also have larviparous birth - Females produce larvae directly instead of eggs

True or False. For a free-living, terrestrial nematode, the selective advantage of a cuticle is that it increases surface area for digestion.

False

Phylum Nematoda Dissection Tips

Flat structures - intestine Thin and numerous (Spaghetti-like) structures - male = testes - female = ovary/oviduct Large tube structures - male = seminal vesicle - female = uterus (bifurcated/paired)

What type of skeleton do nematodes have?

Hydrostatic skeleton fluid filled pseudocoel

longitudinal muscle derived from mesoderm

Identify the type of tissue indicated by line E.

Free-living Nematodes (marine)

Marine nematodes are exclusively meiofaunal, and there are no known parasitic marine nematodes (although some are "semi-parasitic") - Meiofaunaà microscopic animals or protists that are small enough to live between sand grains Important ecosystem functions and services - e.g. bioturbation, enhanced mineralization of organic matter, sediment stability Important bio-indicators Dominate the meiofauna - More than 50% of meiofauna are nematodes Important link in the food web from microfauna to macrofauna

Compare the motion of the vinegar eels that you observed to the motion that you saw in the earthworms. What is the reason for the difference in the way Nematoda and Annelida like earthworms move? a) They both have longitudinal muscles so the differences are in the environment they live in b) no differences they move the same way c) Nematoda only have longitudinal muscles, while Annelida earthworms have both longitudinal and circular muscles

Nematoda only have longitudinal muscles, while Annelida earthworms have both longitudinal and circular muscles

Phylum Nematoda Economical Relevance

Nematodes infect plants and reduce crop yields Responsible for more than 15% of crop loss each year Can also be good for crops

Nematodes locomotion

Nematodes only have longitudinal muscles, while earthworms have both longitudinal and circular muscles. Nematodes are not capable of crawling, or even sliding like a snake, because all of their muscles are parallel with the body. Their movement is therefore, in a whip-like motion.

What type of muscles do annelids have?

ONLY longitudinal muscles

Phylum Nematoda Trychinella spp.

Parasitic genus of nematode causing trichinosis (parasitize via formation of cysts)

Phylum Nematoda Ascaris sp. (large roundworm of pig)

Parasitic nematode Eggs ingested by pigs and juveniles migrate to lungs - can parasitize humans as well Cryptobiotic eggs - Can stay viable for extended periods of time

Which phylum has both longitudinal and circular muscles?

Phylum Annelida

Are nematodes parasitic?

Some are

Ecdysozoans

The Ecdysozoa comprise one of the major groups within the animal kingdom, and it is also the largest since it includes both the nematodes and the arthropods (insects, spiders, and crustaceans). Ecdysozoans build a cuticle and does not require a source of minerals for its construction. The name Ecdysozoa refers to the fact that many members of this group regularly shed their cuticle, a process called ecdysis that is controlled hormonally.

Online Lab Phylum Nematoda Ascaris esophagus c.s.

The pharynx functions as a pump, generating pressure to force food into the intestine, necessary because the interior of the nematode is at higher pressure than the surrounding environment.

reproductive system ovaries

To what system does the structure indicated by line D belong?

True or False. For a parasitic organism such as Ascaris the selective advantage of a cuticle is that it provides a protective measure against digestion from the host.

True

True or false. A pseudocoelom is lined on one side by mesoderm and on the other side by endodermally derived tissue (gastrodermis). A true coelom is lined on both sides by mesoderm.

True

ovaries

What is structure A?

uterus

What is structure A?

biramous uteri

What is structure B?

lateral line

What is structure B?

intestine

What is structure C?

ovaries

What is structure D?

ventral nerve cord

What is structure F?

Female Ascaris

What is this a cross-section of?

Male Ascaris

What is this a cross-section of?

Pharynx Ascaris

What is this a cross-section of?

Online Lab Phylum Nematoda Female Ascaris c.s.

White arrows are pointing to lateral lines Hint: the intestine is typically found closer to the dorsal nerve cord

Online Lab Phylum Nematoda Male Ascaris c.s.

White arrows are pointing to lateral lines Hint: the intestine is typically found closer to the dorsal nerve cord

Phylum Nematoda Features Pseudocoelomates

With a pseudocoelom, a fluid-filled body cavity - Lies between a layer of muscles and the gastrodermis Body fluids bathe the organs and receive their nutrients and oxygen from the fluid in the cavity

Do nematodes have a cuticle?

Yes Tough outer cuticle is shed (ecdysis)

What are habitats where Nematoda are found and Annelida are not? a) Inside plants b) Inside animals c) In soil d) In freshwater e) In ocean sediments

a) Inside plants b) Inside animals There are no endoparasitic annelids.

Which of these are evolutionary advancements of Nematoda over Platyhelminthes? a) Nematoda have a complete digestive tract b) Nematoda are triploblastic c) Nematoda are deuterostomes d) Nematoda had a pseudocoelom

a) Nematoda have a complete digestive tract d) Nematoda had a pseudocoelom (1) Roundworms possess a completedigestive tract and (2) a pseudocoelom. Both Nematoda and Platyhelminthes are triploblastic. Neither Nematoda nor Platyhelminthes are deuterostomes, they are both protostomes.

Which of these are major features that Nematoda shares with Platyhelminthes? a) Radial symmetry b) Endoparasitism c) Triploblasts d) Pseudocoelom

b) Endoparasitism c) Triploblasts These two phyla share: - Bilateral symmetry - Endoparasitism - Triploblasts - Protostomes

In many parasitic species the sex ratio of males to females is skewed (not 1:1). Parasitic nematodes often have female-biased sex ratios, Can we explain these departure from the Fisherian expectation of 1:1 sex ratio? a) Individuals within a single host are more closely related - group-level selection (closely related parasites within a host), so having a female biased sex ratio reduces competition among brothers for mates b) In parasitic nematodes, sex ratios at birth are unbiased and it looks as though observed sex bias is caused by higher female survivorship c) Female offspring are cheaper to produce than males

b) In parasitic nematodes, sex ratios at birth are unbiased and it looks as though observed sex bias is caused by higher female survivorship c) Female offspring are cheaper to produce than males

Which of the following is an accurate description of the phylum Nematoda? It's members are...? a) Morphologically diverse, diverse in way of life b) Not morphologically diverse, diverse in way of life c) Morphologically diverse, not diverse in way of life d) Not morphologically diverse, not diverse in way of life.

b) Not morphologically diverse, diverse in way of life

Why do you suppose the digestive system of Nematoda is rather unspecialized compared to Annelida like an earthworm ? a) Digestion is extracellular so no need for additional internal digestive resources b) Organic products they consume require little digestion c) Nematoda don't digest at all, they just defuse nutrients from their environment

b) Organic products they consume require little digestion Because the organic products that nematodes ingest require little additional digestion to access their nutrients.

What type of symmetry do nematodes have?

bilateral symmetry

Which of the following is found in both Annelida and Nematoda? a) Metamerism b) Parapodia c) Longitudinal muscles d) Circular muscles e) Pseudocoel

c) Longitudinal muscles

Which of the following is found in Nematoda and not in Mollusca? a) muscles b) central nervous system c) cuticle d) bilateral symmetry e) radial symmetry

c) cuticle

Which of the following is the finding about the evolution of parasitism in nematodes? a) parasitism evolved once in nematodes b) parasitism of plants and parasitism of animals each evolved once, separately c) nematode parasitism evolved multiple times in each type of host (plants, verts, inverts) d) nematode parasitism evolved once in plant hosts but multiple times in animal hosts

c) nematode parasitism evolved multiple times in each type of host (plants, verts, inverts)

What type of nervous system do annelids have?

cerebral ganglion dorsal and ventral nerve cords

Based on the study mentioned in the introduction, the ancestral nematode was probably a) a plant parasite b) a vertebrate parasite c) an invertebrate parasite d) free-living

d) free-living

Which of the following organ systems are found in Nematoda? a) circulatory b) respiratory c) endo-skeletal d) reproductive

d) reproductive

Have does excretory/osmoregulation work in nematodes?

diffusion

How does respiration and circulation work in nematodes?

diffusion

larviparous birth

females produce larvae directly instead of eggs

cryptobiotic eggs

live for really long time, very resistant

Are annelids endoparasitic?

no

What type of organization do organisms in Phylum Nematoda have?

organ level

Are Nematodes protostomes or deuterostomes?

protostomes

Cuticle of a Terrestrial Free-Living Nematode

provides a protective barrier to reduce desiccation and prevent dehydration in a terrestrial free-living nematode

Are nematodes coelomates, pseudocoelomates, or acoelomates?

pseudocoelomate

ecydysis

shedding or molting the tough, external body cuticle

Are Phylum Nematoda diploblastic or triploblastic?

triploblastic

Are nematodes segmented or unsegmented?

unsegmented