Range: Cosmopolitan Habitat: Tidal waters, deep waters, polar waters, tropics, freshwater, saltwater, and more Size: About 0.5 inches - 11 feet (1.27cm-3.35m) long Diet: Organic particles Threats: Sea turtles, fish, nudibranchs, and more Life span: Theorized to reach hundreds or thousands of years

Transcript:

Today on Animal Fact Files we’re talking about sponges. These animals were originally believed to be plants. To be fair, they’re pretty weird as far as animals go. They don’t have muscles, or nerves, or even organs. They also can’t really move. Sponges are some of the simplest multicellular animals known today and they’ve been around for a long, long time.

Sponges have cells that can change their role even after those cells have been previously performing another role. This would sort of be like if a human’s liver cells suddenly changed into brain cells. Obviously, and thankfully, this can’t happen in humans, but it’s a no brainer for sponges - do you get it… because they don’t have… nevermind.

Zooming back out from cells, looking at sponges as a whole, there are currently thousands of classified species and they’re grouped into three main categories. There are sponges whose skeletons are composed of calcium carbonate, sponges whose skeletons are composed of silica - this group encompasses a majority of the sponge species - and there are other sponges whose skeletons are made out of a special kind of silica. This third group is commonly referred to as the glass sponges, and we’ve talked about them previously.

Sponges can come in all kinds of shapes and colors. In fact, their shapes can vary so drastically even between individuals of the same species that the shape of a sponge isn’t always a great indicator of identity. A sponge species may have differently shaped members based on the environments in which they’ve settled - while one individual may be a creeping shapeless mass, the other may have formed into a tube: it all just depends on where they grew up!

Sponges are found from tidal areas to deep water, from polar regions to the tropics, and from freshwater to saltwater. Heck, they even live in pineapples under the sea! Sponges are most often found on the bottom of the water column and they are unable to move from where they grow. They also come in many colors, and like giant clams can get some of their color from algae.

Young, larval sponges are able to move, but once they find a good spot to settle they’ll stay there for life - unless, of course, they break off a piece of themselves to release to the whims of the currents. Sponges reproduce both asexually and sexually. They may bud like the coral polyps we’ve discussed in a previous episode. Some freshwater sponge species will release pieces of themselves which can withstand harsh environments and won’t settle and start growing until conditions become more favorable. It’s believed this is part of how freshwater sponge species are able to spread out.

Most sponges are hermaphroditic like slugs and snails, and like these gastropods they’ll still reproduce with another member of their species. Sponges will release sperm into the water column which is then pulled in by another sponge where it’s transported to that sponge’s eggs.

Sponges have pores; their scientific name means “pore bearing”. Sponges create currents through their bodies using special cells that have tail-like structures called flagella. The current brings water in through smaller pores, moves it through the sponge’s body - during which cells will collect particles of organic material that acts as sponge food - and then pushes it out the sponge’s larger pores.

Most sponges eat in this way, though there are some who catch crustaceans on a velcro-like outer layer. Generally speaking, sponges aren’t nutritious or tasty, but they are taken by nudibranchs, sea turtles, and other adventurous animals. Sponges are also believed to live to be hundreds if not thousands of years old.

For more facts on sponges check out the links in the description. Thank you to Molly for today’s request! Give a thumbs up if you learned something new today, and thank you for watching Animal Fact Files.