Class Asteroidea (starfishes) - Pisaster ochraceous, - Pisaster giganteus , - Pi
ID: 261872 • Letter: C
Question
Class Asteroidea (starfishes) - Pisaster ochraceous,
- Pisaster giganteus,
- Pisaster brevispinus,
- Asterina miniata,
- Linckia columbiae,
- Acanthaster planci
and class Crinoidea (sea lilies)
Where are the ambulacra on each organism?
What shape are the tube feet? Do they have suckers? How does the animal use its tube feet?
What are the extents of the oral and aboral surfaces on each animal?
Whic classes of echinoderms are rigid and which are flexible? How do their skeletal systems differ?
What do their various animals eat? How do they obtain their food? Where is the mouth? What are the characteristics of the digestive system of each class?
Thank you
Explanation / Answer
Ambulacral groove is present on their oral side of all the organism given. Tube feet are active tubular projections in all these animals. These animals used the tube feet for respiration, feeding and locomotion. Yes, they have sucker. Oral and aboral surfaces are present on the right and left sides of bilateral symmetrical each animal.
Asteroidea, Ophiuroidea, Echinoidea and Holothuroidea are rigid whereas Crinoidea is free. Most of the animals feed on molluscs. They obtain their food by the suckers. Mouth is centrally placed on the oral surface of the body. All the animals have complete digestive system as it start from mouth and end in anus. They have not mouth, oesophagus, two-part stomach, intestine and rectum.