bilateria (protostomes and deutrostomes)

Question 1

what is bilateral symmetry?

Answer 1

have a left and a right
symmetry along a long axis

Question 2

purpose of bilateral symmetry

Answer 2

directionality
- creates an anterior and posterior
- dorsal and ventral
- left and right

Question 3

3 layers of cells in bilateria

Answer 3

ectoderm - epidermis and nerves
endoderm - digestive tract
mesoderm - muscles and connective tissue

Question 4

2 divisions of the bilateria

Answer 4

protostomia
- mouth first
- blastopore becomes mouth

deuterostomia
- mouth second
- blastopore becomes anus

Question 5

deuterostomes

Answer 5

radial cleavage
blastopore becomes anus

enterocoelom - forms from an outcropping of gut
some have gill slits in pharynx

split into ambulacraria
and chordata

Question 6

protostomes

Answer 6

spiral cleavage
blastopore becomes mouth

interior cavity called schizocoelom

split into ecdysozoa
and spiralia

Question 7

spiralia (protostomes)

Answer 7

spiral cleavage

split into gnathifera and lophotrochozoa

Question 8

ecdysozoa

Answer 8

arthropods
nematodes

grow by ecdysis - moulting exoskeleton
lack locomotory cilia
teeth within foregut breakdown food
ring of spines around mouth capture food

Question 9

branches of ecdysozoa

Answer 9

priapulida
kinorhyncha
nematomorpha
Nematoda
loricifera

Question 10

panarthropoda

Answer 10

super phylum within ecdysozoa

includes arthropods

and tactopoda
- onychophora
- tardigrada

Question 11

tactocoda - onychophora

Answer 11

velvet worms

worm like segmented body
head made of 3 segments

indirect internal fertilisation

Question 12

tactopoda - tardigrada

Answer 12

tardigrades or water bears
minute animals found in all biomes

four body segments
paired appendages
exoskeleton

no respiratory system
haemocoel - body cavity filled with blood, oxygen dissolved in it

cryptobiosis - tun
hard to kill or dehydrate
survive extreme temperatures