Topic 13a - Animals I: Invertebrates

Question 1

Key features of animals?

Answer 1

Multicellular
No cell wall
Heterotrophic
Reproduce sexually
Motile at some point in their lives
Can respond rapidly to external stimuli
All animals have an upper (dorsal) and lower (ventral) surface

Question 2

Major evolutionary advances?

Answer 2

Tissues
Radial=>bilateral symmetry
Protosome=>deutrosome body plan
cuticle moulted => cuticle not moulted

Question 3

The only animal w/out tissue is?

Answer 3

A sponge (extant group)

Question 4

A bit about the development of tissues?

Answer 4

Organisation of cells into groups that function as a unit

Coincident w/ development of symmetry

Question 5

Symmetry is described as which 2 types?

Answer 5

Radial

Bilateral

Question 6

Which animals have radial symmetry?

Answer 6

Cnidarians (sea jelly, coral, anemones)

Ctenophores (comb jellies)

Question 7

Which animals have bilateral symmetry?

Answer 7

All except cnidarians & ctenophores

Question 8

Radially symmetrical animals have?

Answer 8

2 germ layers
typically sessile or drifters
sensory organs distributed evenly around body
no body cavity

Question 9

Bilaterally symmetrical animals have?

Answer 9

3 germ layers
typically motile
sensory organs & neurons concentrated in head region (cephalisation)
often possess body cavity

Question 10

Animals w/ bilateral symmetry have how many body plans? Names? Description?

Answer 10

3.
Acoelomates: no separation b/w body wall & digestive tract

Coelomates: digestive tract is in cavity lined completely w/ mesoderm

Pseudocoelomates: body cavity is partially lined w/ mesoderm

See lect. diagram

Question 11

The distinction b/w protosomes & deutrosomes is based on?

Answer 11

embryonic development

Question 12

A bit about Protosomes?

Answer 12

“first mouth”

• invagination at gastrula stage becomes the mouth
• incl. roundworms, flatworms, segmented worms, molluscs, arthropods

Question 13

A bit about Deutrosomes?

Answer 13

“second mouth”

• invagination of gastrula becomes the anus; mouth forms secondarily
• incl. echindoderms & chordates

Question 14

A bit about moulting in protosomes?

Answer 14

Cuticle is shed periodically (arthropods, roundworms)

Cuticle is not shed (flatworms, segmented worms, molluscs)

Question 15

List of invertebrates: (phylums)

Answer 15

Porifera
Cnidaria
Platyhelminthes*
Annelida
Mollusca
Arthropoda*
Nematoda
Echinodermata

Question 16

A bit about phylum porifera?

Answer 16

Sponges
mainly in saltwater
repro is sex. or asex. (budding)
No true tissues, but 3 cell types:
epithelial (outer surfaces)
collar (Move h2o through pores via flagella for filtering)
ameboid (move b/w epithelial & collar, digest food, move nutrients around, produce repro cells)

Question 17

A bit about phylum cnidaria?

Answer 17

jelly fish, anemones, coral
mostly saltwater
all are carnivores -use stinging cells

Two tissue types:
contractile
nerve

Two basic body plans:
polyp (sessile, tubular)
medusa (floating, bell shaped)

Question 18

A bit about phylum platyhelminthes? **

Answer 18

Flatworms
free living or parasitic
repro sex. or asex (regeneration)
most are hermaphroditic & can self fertilise
possess simple tissues (eye spots, ganglia, nerve cord)
No circulatory or respiratory systems

Question 19

A bit about parasitic platyhelminthes?

Answer 19

Repro, sexually
Major groups: cestodes (tapeworms) & trematodes (flukes)
Require primary & secondary hosts
-primary is usually vertebrate digestive tract
-2ndary can be vertebrate (tapeworm) or mollusc (fluke)

Question 20

A bit about phylum annelida?

Answer 20

segmented worms
segmented body
-contributes to complex movement
-each seg. has same muscle groups. excretory organs etc
Repro is sex. (two sexes or hermaphro) or asex (regen)
Closed circulatory system
Tubular, one way gut.
Ladder like nervous system (simple brain in head region, paired ganglia in each seg.)

Question 21

A bit about phylum mollusca?

Answer 21

clams, snails, slugs, squids, octopods
sessile or motile
open circulatory sys.
Simple nervous sys.
repro is sex.
3 major groups:
-gastropods (snail/slug)
-Bivalves (clams, scallops, mussels, oysters)
-Cephalopods (squids, octopuses, cuttlefish, nautiluses)

Question 22

A bit about phylum arthropoda?**

Answer 22

insects, spiders, arachnids, myriapods & crustaceans
“joint-legged” animals
possess exoskeleton that is periodically shed

Question 23

special adaptations of arthropods?

Answer 23

Body segments organised in tagma (head, thorax, abdomen)
Tracheal system for gas exchange (series of 02 carrying tubes)
cuticle to prevent water loss
wings for flight (insects)
Metamorphosis (transition through very different life forms adapted for diff. purposes:
-larva (obtaining nutrients)
-pupa (transitional stage)
-adult (repro)

Question 24

A bit about phylum nematoda?

Answer 24

roundworms
ubiquitous (?)
Decomposers or parasites
simple structure-no circulatory sys.
-no respiratory sys.
Repro is sex.
Parasites can cause disease of plants or animals