Ctenophora

Question 1

Habitat and Lifestyle

Answer 1

Holo planktonic
All marine
All predatory
mm to 1.5 m

Question 2

Anatomy

Answer 2

8 bands of complex cilia from aboral to the oral surface (comb rows)
2 tentacles within the tentacle sheath impose bilateral symmetry

Question 3

Locomotion

Answer 3

Use comb plates for locomotion
They move entirely by ciliary movement
The largest animals known to locomote by cilia

Question 4

Digestive System

Answer 4

Food enters at the mouth where it passes into the pharynx then the stomach
Initial parts of digestion occur within the gastrovascular canals
Finally passing out the anal pores

Question 5

Feeding

Answer 5

Use of long tentacles with tentilla to release collocytes which have a sticky adhesive to capture prey in a net
Retract tentacles then spins body to waft tentacles over the mouth

Question 6

Nervous System

Answer 6

Nerve net in epidermis & mesoglea
Aboral sensory organ (rudimentary brain)
This is essentially a gravity receptor formed of a statolith, dome and balancer that communicates with the comb rows

Question 7

Venus’s Girdle (Cestum spp.)
Lobate Ctenophores (Mnemiopsis)
Beroë

Answer 7

Up to 1.5 m in length

4 muscular lobes on either side of the mouth for feeding (invaded black sea)

Has no tentacles, just a large swimming mouth with macrociliary teeth. It was introduced to combat Mnemiopsis

Question 8

Reproduction and Development

Answer 8

Asexual - benthic ctenophores only

Sexual - simultaneous hermaphrodites, broadcast spawn gametes, larva looks like Pleurobranchia