Lecture 5: Invertebrate Diversity

Question 1

Major Metazoan clades

Answer 1

Metazoa
Eumetazoa
Bilateria
Deuterostomia (includes vertebrates)
Protostome
Lophotrochozoa
Ecdysozoa

Question 2

Invertebrates are

Answer 2

animals that lack a backbone; 95% of known animal species

Question 3

Porifera

Answer 3

sedentary animals in both fresh and marine waters; lack true tissues and are suspension feeders

Question 4

Cnidaria (eumetazoa)

Answer 4

• all animals except sponges belong to Eumetazoa, animals with true tissues
• both sessile and motile forms
• diploblastic, radial body plan

Question 5

platyhelminthes (lophotrochozoa)

Answer 5

tripoblastic; acoelomate; free-living or parasitic (tapeworms, flukes)

Question 6

syndermata

Answer 6

pseudocoelomates; rotifers w/alimentary canal; acanthocephalans are parasites

Question 7

lophophorates

Answer 7

coelomates w/lophophores: feeding structures w/ ciliated tentacles; aquatic; sessile

Question 8

Cnidarian body plan

Answer 8

• sac with a central digestive compartment, gastrovascular cavity
• two variations: the sessile polyp and motile medusa
• single opening functions as mouth and anus
• nematocysts (stinging part)

Question 9

Cnidaria is divided into two clades:

Answer 9

Anthozoa and Medusozoa

Question 10

Anthozoa

Answer 10

• are full time polyps

Question 11

Medusozoa

Answer 11

• within medusozoa, Scyphozoa and Cubozoa spend most or all of their life cycles in the medusa form

Question 12

Cnidaria have tentacles armed with cnidocytes which are

Answer 12

specialized cells that immobilize prey

Question 13

Bilateria

Answer 13

• animals have bilateral symmetry and triploblastic development
• clade Bilateria contains Lophotrochozoa, Ecdysozoa, Deueterostomia

Question 14

Phylum Platyhelminthe

Answer 14

• live in marine, freshwater, and damp terrestrial habitats
• flatworms are acoelomates
• flattened dorsoventrally and have gastrovascular cavity
• gas exchange takes place across the surface, protonephridia regulate the osmotic balance
• lack a circulatory system but fine branches of the gastrovascular cavity distribute food to cells

Question 15

example of Platyhelmenthes

Answer 15

Planeria

Question 16

Phylum Mollusca

Answer 16

1. most molluscs are marine, some inhabit fresh water and some are terrestrial
2. soft-bodied animals, most are protected by a hard shell
3. all have a similar body plan with three main parts:
   - muscular foot, visceral mass, and mantle
4. many have a water-filled mantle cavity, and feed using a rasplike radula
5. most molluscs have separate sexes with gonads in the visceral mass
6. cephalopods have a closed circulatory system