Sperm cells are released into the water and fertilise ova which are either also released into the water or retained by the mother and fertilised internally. They are also heterotrophic although some species of sponge are carnivorous and eat small crustaceans, most of the 5’000 known sponges are passive feeders, they get their energy by breaking down bacteria from the water that they filter through their body.įurthermore they reproduce sexually. The video below shows how effective this filtration system is: These cells have “whip-like” flagella which line their pores and help the passage of water through their water flow systems. And despite the fact they don’t have differentiated tissues, they do have specialised cells, such as choanocytes.

Although sponges have no body symmetry and no tissues or organs, they are multicellular and eukaryotic. So how do sponges fit into this definition? Surprisingly much better than you probably think. They are mobile at some point during their development.they can distinguish between foreign tissue and their own They have a body which has some form of symmetry, and is differentiated into tissues.They are heterotrophic – they cannot produce their own energy and must ingest other organic matter.They are eukaryotic (basically their cells are separated into compartments and their DNA is isolated in a nucleus) and multicellular.It may surprise you to learn that sponges are considered animals, after all they don’t seem to possess any of the attributes we normally associate with animals and on the surface resemble plants more than anything else, even Aristole thought so! Which leads me to the question what actually is an animal? Well animals generally have the following characteristics: The invertebrates being tackled this week are a rather large, diverse and incredibly successful group – the sponges. Clockwise from top left: (1) Stovepipe sponge, (2) Orange tube sponge, (3) Azure vase sponge, (4) Harp sponge and (5) Orange elephant ear sponge

Can the azure vase sponge move