Pictures of species are included where available. Sponges are aggregations of cells that do not form tissues or layers but are organized around a system of pores, canals and chambers. They form soft spongy mats riddled with pores , some volcano-like. Sponges are found on and under rocks and on floats and pilings. Urticina crassicornos Metridium sp.
Flatworms are thin flat and oval.
They are usually 2 to 3 times longer than wide and are usually less than 5 m long. They swim by undulating wave-like motions of the margins of the body. It is difficult to identify species or even genera in the field. These worms are not segmented . 1 m. A unique feature of this group is the presence of a proboscis - a tubular apparatus for capturing prey.