Loading...

What are the characteristics of sponge skeletons?

There are three main types of sponges--calcareous, glass, and desmosponges. Taxonomists group sponges according to their skeletons.  Sponge skeletons are not very similar to rigid human skeletons; they are flexible, elastic, and expansive.

Some sponges have spicules, which are tiny needle-like structures, embedded within their mesohyl. The class the sponge is grouped into is determined by the material the spicules are composed of.

In the activity below, click each tab to learn about the skeleton of each type of sponge.

Calcareous Sponges

Glass Sponges

Demosponges

By Philippe Bourjon (Don de l'auteur) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Calcareous sponges, like the one pictured, contain spicules of the hard mineral calcium carbonate.  They are the smallest of the sponges.   

By dphershman (Cloud Sponges) [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

Sponges in the class Hexactinelid are called glass sponges. Glass sponges have spicules composed of  silica, which is a material that's similar to glass.  The bright yellow sponge pictured is a glass sponge.  Note the shiny texture of the sponge--this is the silica.  Because glass sponges are delicate like glass, they live very deep in the ocean, avoiding the destructive currents.  Also pictured are drawings of these delicate and elegant animals.

By Parent Géry. (Own work.) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia CommonsBy Philippe Bourjon (Don de l'auteur) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Demosponges, such as the ones pictured, are the largest and most common of all sponges.  About ninety percent of all sponges are demosponges.  Demosponges have a skeleton made up of spongin, which is a flexible protein fiber.  Some demosponges also contain spicules of both silica and calcium carbonate.

In the activity below, match the word or phrase on the left with its definition on the right by dragging the corresponding circles.  

spongin
flexible protein

calcium carbonate spicule

silica spicule

Correct, spongin is a flexible protein.
Spongin is a protein and is not a tiny needle or spicule.
spicule
flexible protein

type of sponge

tiny needle

Correct, spicules are tiny needles made of either calcium carbonate or silica.
Spicules are tiny needles found in glass and calcareous sponges.
silica spicule
found only in demosponges

found in calcareous sponges

found mostly in glass sponges

Good job, glass sponges contain spicules of silica.
Glass sponges contain spicules of silica.
calcareous sponges

have calcium carbonate spicules

have silica spicules

have a skeleton made of spongin

Calcareous sponges have skeletons made of spicules of calcium carbonate.
Spongin is associated with demosponges and silica spicules are found in glass sponges.

Complete