/ \ I ERTEBRATES. SPONGES 



39 



Marine Habitat Group. A community of starfishes, 

 sponges as seen below the edge of a coral reef in the Bahamas 



sea anemones, sea urchins, corals and 



This alcove contains the lowest forms of animal life. All are single- 

 celled individuals. The simplest kinds are abundant in swamps and 

 stagnant water, others are found in myriads in the sea while the ocean 



bottom in many localities is covered with them. The specimens 

 p . exhibited in this alcove are mainly models, some of which are 



enlarged more than a thousand diameters. 

 Sponges are principally of two kinds — those with skeletons or sup- 

 porting structures of silica (i. e. flint) and those with skeletons of horn. 

 The sponges of commerce belong to the latter class. In the specimens 

 exhibited the skeleton only can be seen, the living tissue having been 



removed. Many of the "glass" sponges are very beautiful in 

 Alcove 2 design. Sponges range in size from the tiny Grantia of the New 

 Sponges England coast to the gigantic "Neptune's goblets" found in the 



eastern seas. This alcove contains certain specimens whose tis- 

 sue is represented in wax tinted to show the natural coloring of sponges, 

 which varies from the bleached yellowish color commonly seen to deep 

 brown or black, or yellow and red, in varying shades. 



