all key characteristics

Question 1

Porifera

Answer 1

1. metazoa - without true tissues or organs 2. asymmetrical 3. totipotent cells (give rise to any cell type) 4. body formed of monolayer of cells surrounding a secreted matrix 5. choanocytes driving aquiferous system??? 6. adults sessile filter feeders 7. larval stages motile and lecithotrophic

Question 2

Cnidaria

Answer 2

1. Radially symmetrical 2. Diploblastic 3. Possess cnidae (sting) 4. Single body cavity 4. No nervous system - Nerve net 5. Alternation of generations Asexual polypoid and sexual medusoid stages 6. Cilliate planula larvae

Question 3

mollusca

Answer 3

1. Buccal region with radula, ribbon like, heavily modified. 2. Through gut (complete, regional specialisation) and kidneys 3. Gas exchange by ctenidial gills housed in mantle cavity 4. Separate sexes (dioecious) 5. Trochophore and veliger larva

Question 4

nemertea

Answer 4

1. Bilaterally symmetrical 2. Triploblastic 3. Tissues, organs, complete nervous system, and closed circulatory system surrounding a through-gut 3. Dioecious [males and females] 4. Unique proboscis 5. Rhynchocoel (different to annelids)

Question 5

nemata

Answer 5

1. Bilaterally symmetrical, 2. triploblastic 3. Body more than two cell layers thick: Tissues, organs, nervous system, and through-gut No circulatory or gas exchange systems 4. Unique sense organs Amphids (anterior, open) Phasmids (posterior, open) Deirids (lateral, closed) 5. Dioecious

Question 6

bryozoa

Answer 6

1. Bilaterally symmetrical 2. Triploblastic, Trimeric (tripartite), Enterocoelic coelomates Tissues, organs, Through, U-shaped gut, nervous system but no circulatory system or respiratory pigments 3. Gas exchange via lophophoral tentacles Colonial 4. Sexual reproduction 5. Asexual budding

Question 7

hemichordata

Answer 7

1. Bilaterally symmetrical 2. Trimeric Tissues, organs, nervous system (with mesodermal nerve chord), open circulatory system and excretory structure 3. Ciliated pharyngeal [in pharanxy] gill slits [tell you about species you’ve got.] 4. Through (enteropneusta), or U-shaped gut (pterobrancia) 5. Dioecious 6. Tornaria larvae, unique to Enteropneusts

Question 8

urochordata

Answer 8

1. Bilaterally symmetrical, may be lost as adults 2. Triploblastic Tissues, organs, and circulatory system with heart, but no excretory organs or coelomic body cavities 3. Nervous system with a hollow ‘notochord’ in free-swimming larval stages 4. Pharyngeal gill slits (like the enteropneusta) 5. U-shaped gut 6. Hermaphrodites

Question 9

crustacea

Answer 9

1. Bilaterally symmetrical 2. Body more than two cell layers thick Tissues, organs and circulatory system 3. Nervous system 4. Body comprised of a five-segmented cephalon (with compound eyes), thorax and abdomen Cephalic shield or carapace present 5. Jointed, biramous appendages 6. Three pairs of mouthparts 7. Through, straight gut with digestive ceca 8. Gas exchange by aqueous diffusion across specialised branchial surfaces 9. Separate sexes or hermaphrodites 10. Nauplius larva [the use of the appendages of the head (the antennae) for swimming. The nauplius is also the stage at which a simple, unpaired eye first appears.

Question 10

annelida

Answer 10

1. Bilaterally symmetrical and vermiform 2. Segmented with growth from teloblasts 3. Trimeric or tripartite Triploblastic (ectoderm, mesoderm and endoderm) 4. Tissues, organs and closed circulatory system Respiratory pigments (haemoglobin, chlorocruorin and hemerythrin) 5. Nervous system Wide array of sensory receptors Dorsal cerebral ganglion or simple brain 6. Lateral, epidermal chaetae 7. Gonochoristic or hermaphroditic Trochophore larva

Question 11

echinodermata

Answer 11

1. Calcareous, mesodermally derived endoskeleton 2. Radially symmetrical Pentamerous (5 rays/ sides [moving out from central disc]) Oral/aboral axis [mouth is on underside, against sediment surface]] 3. Embryogeny deuterostomous (mouth second) [mouth opens second. Blastopore forms anus not the mouth] Blastopore typically forms the anus not the mouth 4. Triploblastic (ectoderm, mesoderm and endoderm) 5. Tissues, organs, circulatory system and non-centralised nervous system [no definitive head for brain to develop. Series of nerve nets and other adaptations] 6. No excretory organs [across body wall] 7. Coelomic water vascular system 8. Complete through gut but anus sometimes absent 9. Dioecious, some hermaphroditism 10. Bilaterally symmetrical larvae