Sponges are an
animal, they are classified in the
phylum Porifera and can be found in almost all
salt water seas. Unlike most animals, sponges generally are
immobile, although they do have a few tricks to get around. Some seem to creep tiny, tiny distances (up to 4 mm per day) while others
hitch a ride by attaching to the shell of more mobile creatures.
Even though a sponge is a
creature, not an aggregate of creatures like
coral it is held together so loosely it can be shaken apart. It is not considered to have separate types of “
tissues”.
1
Sponges eat and oxygenate by tiny
flagella which wave and move huge volumes of water (and the tiny creatures and oxygen carried in the water) through the “nooks and crannies” which all lead to a central open spot where wastes exit. Some sponges
filter up to 90% of the
bacteria in the water, others feed more on other organic matter or have
symbionts such as
green algae that contribute
nutrients. One type of sponge captures small
crustaceans and engulfs them with cells that then digest them.
Sponges
reproduce using all sorts of strategies. Sexually the are
hermaphrodites and produce eggs and sperms at different times. Sperm is spewed out of one sponge and then sucked into another sponge where it meets up with eggs. They also reproduce
asexually producing
buds, which break off and develop into new sponges.
2
Sponges were historically harvested by very dangerous practices. This resource said 50 % of Greek sponge divers died on any given trip up to the mid 60s when conditions improved considerably. Many of the problems were economic, the boat owners pushed the divers into dangeorus practices. Another was nutrition, they ate scant and stale food and water. One of their survival practices was to use sponges that they harvested to
filter their rotten water.
3
Sponge divers are a great tourist attraction in the gulf coast of
Florida.
1) http://www.animalnetwork.com/fish2/aqfm/1998/jan/wb/default.asp
2) http://www.ucmp.berkeley.edu/porifera/porifera.html
3) http://www.kalymnos-isl.gr/webweaver/info/sponge/human_story.html