Lecture 17

Question 1

5 Criterion for Phyla

Answer 1

Symmetry
Germ Layers
Coelom
Blastopore
Segmentation

Question 2

Symmetry

Answer 2

Bilateral - one plane along which they are symmetrical

Radial - several planes along which they are symmetrical

Question 3

Germ layers

Answer 3

Layer of embryo cells that develops into body features: Diploblastic = two layers
Triploblastic = three layers
in the blastula

Question 4

Coelom

Answer 4

Triploblastic body cavity: 
absent --> acoelomate
present --> coelomate
- fluid filled used as internal support
- transport of fluids
- space for development of internal organs
- increased body size

Question 5

Blastopore

Answer 5

Protostome (blastopore becomes the mouth)

Deuterostome (blastopore becomes the anus)

Question 6

Segmentation

Answer 6

the body is divided into functional segments,

Question 7

Parazoa - Porifera - Sponges

Answer 7

Simple, aquatic
No mouth or gut
No tissue organisation
No nervous system
Mainly filter feeders
Have pinocytes which can engulf larger prey
Sexual and asexual reproduction

Question 8

Eumetazoa - Cnidaria

Answer 8

Hydra, Jellyfish, Corals and Anemones
Radial symmetry
Diploblastic (Mesoglea in the middle)
Unsegmented
nerve net - use nematocysts to catch prey
sexual and asexual reproduction

Question 9

Eumetazoa - Platyhelminthes

Answer 9

Flatworms: two modes of living --> free-living aquatic or parasitic
Four classes: Turbellaria (flatworm), Monogenea (external flukes), Trematoda (internal flukes), Cestoda (tapeworm)
Bilateral symmetry
Triploblastic
acoelomate
protostome (simple gut with mouth only) 
unsegmented 
bottom surface may be covered in cilia

Question 10

Reasons for Arthropods success

Answer 10

Exoskeleton - composed of chitin, protection, support, prevent water loss
Diversification of segmentation - shows fusion and loss of segments
Diversification of appendages
Advanced nervous system
Advanced sensory structures - compound eyes, antennae