An Introduction to the Invertebrates, Second Edition - tiera.ru

WHAT DIFFERENT KINDS OF SPONGE ARE KNOWN?25closely related species of sponges. Animal skeletons, whetherhard or hydrostatic (based on the incompressibility of water)usually translate muscle contraction into movement. Sponges,however, have no muscles and the supporting skeleton insteadserves to prevent movement from occurring. Spicules havefurther important functions in preserving the sponge’s shape,keeping the pores open and maintaining the internal channels(as well as making the sponge even nastier to eat than itprobably would be anyway).3.2 What different kinds of sponge are known?Calcarea, with calcareous spicules. They occur in shallow waters(less than 100 metres). Examples are Leucosolenia and Grantia(Figure 3.2b,d).Fig. 3.2 Drawings of (a) a hexactinellid, showing spicules fused to form a lattice; (b) Sycon (larger) and Leucosolenia;(c)Halichondria;(d) Grantia.