Polychaete

Question 1

Polychaete features

Answer 1

Marine worms (predominantly) some FW and terrestrial
Parapodia (fleshy projections) on each segment increase SA for gas exchange
-setea stick out of parapodia
Prostomium can be very well developed for feeding
-tentacles and jaws well developed
-fan worm = head developed to catch food that passed

Question 2

Polychaete groups

Answer 2

1. Errant - move around a lot, might be active hunters etc. Free-living, well-developed parapodia and active swimmers
2. Sedentary worms - don’t move but have elaborate heads for food collection, tube-dwelling worms

Question 3

Sedentary worm examples

Answer 3

1. Sabella (fan-worm) has complication sorting mechanism that sorts particles it catches (rejects large)
2. Sand mason - tube that sticks out of sand
3. Arenicola - lugworm, well-developed prostomium but basic features
   - parapodia reduced shows it burrows
   - lives in u-shaped burrow to draw out sand, feeding on it then backing out and defecating there

Question 4

Polychaete reproduction

Answer 4

Dioecious
External fertilisation - M&F swim together and synchronise spawning (specific, like once a year, relating to tide or moon cycles)
Epitoky - metamorphosis into reproductive form
-forms longer parapodia (better swimmer for mate finding)
Devote so much energy their bodies breakdown after
Form trochophore larvae