Zoo-Lab (Sem-1) - Exercise 10: Phylum Porifera

Phylum Porifera

pore-bearing and aquatic animals; diploblastic (didermic) with internal calcareous or silicious skeletons or with spongin fibers or both; mature animals are sessile and tethered to the substratum; although multicellular, they have no organs, and tissues are undefined

substratum

an underlying layer or substance, in particular a layer of rock or soil beneath the surface of the ground

spongocoel

the one body cavity of porifera where numerous pores are connected

oscula

excurrent pores; larger pores that serve as the exit of water from the spongocoel

ostia

incurrent pores; smaller pores that serve as the entrance of water into the spongocoel

Demospongiae; Calcaria; Hexactinellida

representative classes of Phylum Porifera

Class Demospongiae

members possess a skeleton made up of spongin fibers; include commercial sponges

Euspongia officinalis

Demospongiae; common bath sponge; colonial; globose in shape; and permanently attached to the substratum

gastral cavity

of bath sponges; not the digestive cavity, for digestion in sponges is done inside the cells

Haliclona sp.

Demospongiae

Spongia sp.

Demospongiae

Class Calcaria (Calcispongiae)

sponges with skeleton consisting of many spicules made of calcium carbonate

Grantia sp.

Calcispongiae; body cavity is of the sycon type; skeleton is of calcareous type

Class Hexactinellida (Hyalospongiae)

members of this class has a skeleton made up of siliceous spicules, usually with six rays, as the name implies; the spicules are often fused together into a continuous network

Euplectella aspergillum

Venus flower basket; siliceous sponge; attached to the substratum by a mass of glassy threads

sieve plate

covers the osculum

choanocyte

versatile cells; their flagella beat to create the active pumping of water through the sponge, while the collars are the primary areas that nutrients are absorbed into the sponge

asconoid; syconoid; leuconoid

three types of canal systems in sponges

asconoid canal system

simplest system; involves entrance of water through the ostia; then to the spongocoel; then exiting through the osculum

syconoid canal system

a slightly more complex system; the water enters through the ostia into incurrent canals; From there, it passes into radial canals lined with choanocytes (flagellated cells) through prosopyles (tiny openings); the water then enters the spongocoel and finally exits through the osculum

leuconoid canal system

the most complex type of canal system; the water enters through the ostia into incurrent canals, then moves into flagellated chambers through prosopyles; from these chambers, the water enters excurrent canals through apopyles (larger openings) and finally exits through the osculum; this type of canal system allows for a greater surface area for feeding and is found in most large sponges, like Spongilla