Range: Warm, marine waters through the world

Habitat: Hard surfaces including rocks, shells, and more

Size: Up to 1 inch (2.5 cm) thick; 1 foot (30 cm) wide

Diet: Particles filtered from the water column

Threats: Likely typical sponge predators such as nudibranchs, molluscs, and more

Lifespan: Unknown

Transcript:

Today on Animal Fact Files we’re discussing slime sponges. These invertebrates are also known as flesh sponges. This, of course, is not to be confused with skin sponges which we'll have to discuss in another episode. Slime sponges get their common name because they look like bubbly slime smeared across a hard surface. These are encrusting sponges most frequently found on solid substrate such as underwater boulders and sea caves, but they also live on biological surfaces such as other sponges, annelid tubes, mollusc shells, and more. Slime sponges are found in most of the world’s marine water systems. Their highest concentrations are in the Mediterranean, Caribbean, and Indo-pacific. These invertebrates most frequently live in shallow water above 115 feet (35 m), but some individuals inhabit water as deep as 1,000 feet (300 m)! That’s as deep as light can reach into the ocean, and at that depth it’s really, really dark.

Slime sponges come in different colors based on where they live. Those with exposure to direct sunlight often appear red while those in dimmer areas are green to yellow. It’s worth noting, however, that these invertebrates range in color  and may be purple, blue, and even different colors with a creamy base, so their location is not the sole determining factor. These sponges are no more than just over an inch (2.54 cm) thick, but they grow outward along their edges as they creep along the places they’ve attached. Overall, they can reach nearly a foot (30 cm) across. A slime sponge’s surface has many folds, known as lobes. They have no skeletal structure, so no spicules, which are present in many other sponge species and give them their shape. Instead, slime sponges are flexible and described as velvety to touch.

Sea water flows through the sponge’s various lobes and small particles floating in the water column are filtered out as food for the sponge. Both plant and animal matter are consumed; these animals aren’t picky, they’ll eat whatever passes through! Because they filter out just about anything that passes through, they’ll accumulate the materials they can’t expel, such as metals. For this reason, slime sponges can be a helpful indicator of substances in the water column, and they provide a snapshot to scientists about the surrounding water’s pollution levels.

Like many sponge species, slime sponges are capable of both sexual and asexual reproduction. They’re hermaphroditic and both eggs and sperm are present in each individual organism. Slime sponge eggs are retained, and their larvae are expelled into the water column– often during the warmest part of the year. The larvae only live a few days free floating in sea water. They must find a suitable place to settle and develop within that time or else they’ll perish. Asexual budding, which occurs when a clone of the parent organism forms from the parent into a new individual, allows the newly formed sponge to last in the water column for three months which may help them spread out further than their sexually produced counterparts. These sponges can also fragment into pieces and new sponges will form from the fragments.

For more facts on slime sponges, check out the links below. Give a thumbs up if you learned something new today. Thank you to our Patrons SpikeSpiegel93, Dad, and everyone else for their support of this channel! And thank you for watching Animal Fact Files!