Question

Which of the echinoderm classes is characterized by most regionalized digestive tract? Include explanation please

a.) Stelleroidea (Wrong answer)

b.) Holothuroidea

c.) Echinoidea

d.) Crinoidea

Answer 1

a)Stelleroidea has a more differentiated digestive system consisting of a buccal cavity,eosphagus,stomach and an anal vent .However the arrangement is not recoginalized .

b)Holothuroidea digestive tract consists of seven parts and is covered by the epithelial tissues and also has junctions.It consist of the mouth,pharynx,eosophagus,stomach ,cloacal chambers and anal vent .The distribution is highly regionalised in Holothuroidea

c)In Echinoidea the digestive tract just consist of coiled tunes having opening for the mouth and anal cavity .Hence it is not regionalised.

d) In Crinoidea only consist of a one way of a not very regionalised gut system.Hence this option is not right

Hence from the above explanation option b is the right answer