Zoo exam 2 - chapter 12 porifera

General characteristics of sponges

filter feeders, most are marine, use flagellated “collar cells” or choanocytes to move water, means “pore-bearing” - sac-like bodies perforated by many pores, embryos are free-swimming, adult sponges always attached, some appear radially symmetrical (not) and many are irregular in shape, few are predators, many live as commensals or parasites in or on corals

Asconoids

flagellated spongocoels, simplest body form, small and tube shaped, water enters a large cavity (the spongocoel) - lined with choanocytes, example: leucosolenia and clathrina

Syconoids

flagellated canals, resemble asconoids but larger with a thicker body wall, wall contains choanocyte-lined radial canals that empty into spongocoel, spongocoel is lined with epithelial cells rather than choanocytes —> food digest by them

leuconoids

flagellated chambers, most complex and are larger with many oscula, clusters of flagellated chambers are filled from incurrent canals, and discharge to excurrent canals, most sponges are leuconoid, system increases flagellated surfaces compared to volume

How sponges feed

primarily by filtering microscopic particles from water using specialized cells called choanocytes, with nutrients distributed throughout the body by amoebocytes (digested by them)

Class calcarea skeleton

calcareous sponges with spicules of calcium carbonate, spicules are straight or have 3 to 4 rays

class hexactinellida skeleton

glass sponge with 6 rayed spicules of silica

class Demospongiae skeleton

spicules are siliceous and bound together by spongin

Class calcarea

all the body types (asconoid, syconoid, and leuconoid), most are small with tubular or vase shaped, many drab in color but some bright colored

Class hexactinellida

glass sponges, nearly all deep-sea inhabitants, most radially symmetrical, stalks of root spicules attach them to substrate, adapted to a deep-water habitat with a large and easy flow of water

Class Demospongiae

contains 95% of living sponge species, leuconoid body form, freshwater sponges, flourish in summer and die in late autumn