Useful Vocabulary

acelluar - without cells
spongin fibres -flexible skeletal material made up of protein
spicules - supportive needles made up of calcium carbonate
invertebrates - an animal that lacks a backbone
Porifera - the phylum in which sponges are classified in (the Hexactinellida (glass sponges), the Demospongia, and the Calcarea (calcareous sponges))
collar cell - cells that line the interior of the sponge
osculum - a large hole through which water leaves the central cavity of a sponge
amebocyte - the sponge cell that builds spicules from calcium carbonate or silica
spongin - protein that makes up the skeleton of some sponges
gemmule - sphere-shaped collection of amebocytes surrounded by spicules which can grow into a new sponge
budding - asexual reproduction in sponges

Habitat (Where they live, adaptations)

Sponges can be found in almost all water habitats. Although most reside in marine bodies of water, up to 150 different species of sponges have adapted to freshwater climates. Many sponges contain a toxic substance to discourage predators and so other marine animals protect themselves by attatching a sponge to their body where it can grow.

Sponges keep their personal space by releasing the chemicals which avoids competition. Sponges also provide a protective home for many small marine plants, which reside around the sponges pore systems. Some attach themselves to certain corals and molluscs although this is detrimental to the reefs and molluscs. Both degrade and eventually die due to the chemicals and toxins released by the sponge.

Defining Characteristics

Although there are over 5000 different types of sponges residing in the world, they each share similar characteristics. Sponges have a system of pores (also known as ostia) and canals which allows water to pass through freely. This water carries nutrients and oxygen which is vital for the sponge to live. Water also helps waste products to flow out. The movement of the water is initiated by flagellae which are found on special cells known as collar cells.

Sponges can be radially symmetrical or asymmetrical depending on simply their shape. They are held up by a skeleton made up of the protein collagen and spicules. Skeletal elements, choanocytes, and other cells can be found in a jelly like matrix called mesohyl (also known as mesoglea). Sponges have the least complex kind of cellular organization found within parazoans.

General Anatomy

A sponge, although not seeming complex has it's very own complicated body and life style. The anatomy of a sponge is composed of two outer body layers which are thinnly seperated by a gel layer, also called the mesohyl, which is acellular. Spicules or spongin fibers make up the gel layer. Different classes of sponges appear as different shapes but the life functions remain the same as sponges lack both organs and tissues. Sponges are invertebrates and their size ranges from a few milimeters up to two meters tall!






Some examples of spongin shapes:

• tubes
• fans
• cups
• cones
• blobs
• barrels
• crusts