Quiz 15: Polyzoa and Kryptrochozoa

Biology

A Cycliophoran would be found on the mouthparts of marine decapod crustaceans in the Northern Hemisphere.

Differences between ectoprocts and entoprocts are: • Entoprocts have their anus inside the crown of tentacles while ectoprocts have their anus outside the crown of tentacles. • All entoprocts are sessile while some of the ectoprocts can slide or crawl. • Entoprocts are stalked while ectoprocts are not. • Ectoprocts form an exoskeleton around themselves while entoprocts do not. • Ectoprocts form colonies where the colony members are called zooids. This behavior is not seen in entoprocts. • Entoprocts are about 5mm in size while ectoprocts are less than 0.5mm in size.

The distinguishing characteristics of entoprocts are: • They are microscopic, and none is more than 5mm long. • They may be solitary, colonial. But all are stalked and sessile. • All are ciliary feeders. • The body or calyx is cup-shaped, bears a crown of ciliated tentacles. • The body wall comprises a cuticle, cellular epidermis, and longitudinal muscles. • Digestion and absorption occur within the stomach and intestine. • The pseudocoel is largely filled with a gelatinous parenchyma in which is embedded a pair of flame bulb protonephridia and their ducts. • A nerve ganglion is found on the ventral side of the stomach, and the body surface bears sensory bristles and pits. • Circulatory system and respiratory organs absent. • Some species are dioecious, but many are monoecious, most often protandrous hermaphrodites. • Fertilized eggs develop in a depression, or brood pouch, between the gonopore and the anus.

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