Notes

Poriferans (Sponges)
Background Information
These organisms are multicellular organisms that have numerous pores and channels running through their bodies. Sponges are able to resurrect and repeat themselves as means of survival. Sponges consist of a loose federation of cells, which are not considered tissue because cells are relatively unspecialized. They also possess cells that can sense and react to environment but have no real nerve or muscular tissue. Thus, they are considered simple animals.

Movement
Since sponges don't have muscles, they mainly remain sessile. Sessile poriferans are attached to surfaces such as coral reefs or rocks. When they do move, they can only move about 1-4mm per day and this can be contributed to the water currents.

Defense
Due to the poriferan’s minimal movement, they need to have appropriate defense against predators. Mainly, poriferans use spicules to defend themselves, but they are also used for rigidity and structure. Spicules can also be utilized as something similar to a fingerprint. By giving the sponge structure, the sponge won’t be as easily broken. Also, as seen in the picture below, these spicules are pointed like a star. This will poke predators and defend poriferans from being eaten. The shape of spicules vary and are not only limited to the one pictured below.