Sponges

Sponges are only just classed as animals. They have cells that are independent of each other but work together in a colony. It is possible for one single sponge cell to survive, reproduce and create a whole new sponge colony. They are so simple that they do not have any tissue or organs but they do have specialised cells that perform specific functions such as protection, generating a current of water and breaking down pathogens. Sponges are thought to be one of the first animals to have evolved and belong to a phylum of animals known as Porifera.

Where are sponges found?

Almost all sponges are found in marine environments. They live in both shallow coastal water and deep sea environments but they always live attached to the sea floor. Deep sea carnivorous sponges have been found more than 8000 m deep.

How do sponges reproduce?

Sponges can reproduce in a variety of ways, both asexually and sexually. Asexual methods of reproduction include: the growth of stolons that develop into new individuals; a bud separating from the parent sponge and creating a new sponge elsewhere; and the simple act of parts of a sponge breaking of and establishing in a new location.

Sexual reproduction is performed by the fusion of a sperm and an egg. Sperm are released into the water column and enter another sponge before fertilizing an egg. The egg develops inside the sponge until being released as a larva. The larvae are able to move through the water and settle once they find a suitable substrate to grow into an adult sponge.

How do sponges feed?

Specific cells within the sponge have what are known as ‘flagella’. The flagella are used to create a flow of water within the interior of the sponge and that flows out large holes known as the ‘osculum’. The flow of water out of the osculum creates a vacuum that sucks water in through the pores of the sponge. As the water flows through the pores, the sponges filters out small organic matter, bacteria, phytoplankton and protozoans from the water. Some deep sea sponges have evolved carnivorous feeding strategies and trap small crustaceans using hook shaped structures.

Interesting facts:

• A gathering of different sponge species is known as a ‘sleeze’.
• Sponges can filter out as much as 90% of all bacteria that passes through their pores – making them hugely important for disease prevention.
• Many sponges have anti-cancerous properties and have been used to develop various cancer treatments

Last edited: 21 May 2015