Summary
Simple aquatic animals lacking true tissues that filter feed through pores.
In depth
Phylum Porifera. Choanocytes (collar cells) beat flagella to draw water through pores (ostia) and out of the osculum, trapping food. Amoebocytes distribute nutrients and make spicules. They can regenerate and reaggregate from dissociated cells.
Sponges lack organs and nerves. Cells are totipotent. Reproduce sexually and asexually.
Example: sponges are important in reef nutrient cycles.
Sponges have no true tissues or organs, though cells are organised. A body wall of pinacocytes, choanocytes and a gel-like mesohyl with amoebocytes and spicules (calcium carbonate, silica) or spongin supports them. A sponge can filter many times its own volume of water per hour. They reproduce asexually by budding and gemmules, and sexually through sperm released into water, and larvae swim before settling.
If dissociated, sponge cells can reaggregate into new sponges, as shown in 1907 by H. V. Wilson. Sponges host symbiotic microbes that produce bioactive compounds, some leading to drugs such as cytarabine (originally from a sponge). Genomic studies suggest sponges (or possibly comb jellies) are the sister group of all other animals.
Example: glass sponges (Euplectella) have silica skeletons that form a delicate lattice, called Venus's flower basket.
Frequently asked questions
What is Sponges?
Simple aquatic animals lacking true tissues that filter feed through pores.
Which area of biology covers Sponges, and how advanced is it?
Sponges is one of the 53 topics in Zoology & Animal Diversity. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Flatworms, Animal Phylogenomics, Animal Kingdom.
Can you give an example of Sponges?
Bath sponges have flexible spongin fibres.
What should I learn before Sponges?
Sponges is a Beginner topic, so no earlier topic is required. Other Beginner topics in Zoology & Animal Diversity that pair well with it include Animal Kingdom, Vertebrates and Invertebrates, Cnidarians.
What topics are related to Sponges?
The closest topics to Sponges are Flatworms, Animal Phylogenomics, Animal Kingdom, Echinoderms. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Sponges?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Sponges. To practise the whole of Zoology & Animal Diversity, use the Zoology & Animal Diversity quiz.
How is Sponges different from Flatworms?
Sponges: Simple aquatic animals lacking true tissues that filter feed through pores. Flatworms: Soft-bodied, bilaterally symmetric worms with no body cavity, including tapeworms and flukes. Read both side by side and note what each one explains.
How should I study Sponges step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Flatworms and explain the difference aloud. Finally, take the Zoology & Animal Diversity quiz and come back to this page for any question you miss.