Range: Temperate and some tropical seas worldwide

Habitat: Reefs from intertidal zone to about 200 feet (61 m)

Size: Up to a foot (30 cm) long in the oldest, largest species

Diet: Algae such as kelp

Threats: Humans, bacterial infection, sea stars, octopuses, crabs, shore birds, and more

Lifespan: Decades (Thirty or more years typically)

Transcript:

Today on Animal Fact Files we’re discussing abalones. These animals are also known as "sea ears" for their shape. Their shells are shaped like a human ear! Abalones are marine snails with a flattened, spiraling shell. They're gastropods related to other sea snails, nudibranchs, and even octopuses! 

Abalones live in temperate and some tropical oceans around the world. They're reef-dwellers, spending their time scooting along the hard surfaces of the reef in search of their favorite food: algae. These invertebrates live from intertidal zones to depths almost 200 feet (61 m) below the waves, which is the perfect place for algae to grow. Did you know that kelp, those big, long blades of underwater vegetation, is actually algae? Abalones love to eat kelp!

Even on an all-algae diet, these snails can get huge! The largest abalones measure up to a foot (30 cm) across their shell! Of course, it takes a long time to reach this size. Like other snails, the abalone's shell grows with it. It doesn't leave its shell or trade it out for a new one like a hermit crab. The abalone's shell is made of calcium carbonate and inside is a pearlescent substance called nacre. Nacre is also known as mother of pearl, and has been used to decorate jewelry and art. These gastropods can even produce a pearl if an annoying piece of debris lodges in their shell! They'll excrete over the grit to smooth it out.

Unlike some snails who are hermaphroditic, abalones have separate sexes. Males and females spawn by releasing their eggs and sperm into the water column simultaneously. The fertilized eggs are denser than water and sink to the substrate, becoming lodged in cracks and crevices, away from roving predators. The eggs hatch a short time later and the planktonic larvae take just a week to develop before settling to the seafloor and beginning their benthic lifestyle. Female abalones take longer to reach reproductive maturity than males, but overall it takes about three to five years before they're ready to procreate. Even then, these long-lived animals can survive decades if left undisturbed.

Unfortunately, undisturbed they are not. Abalones have faced significant population declines over the past few decades due to overharvesting and poaching. These invertebrates are considered a delicacy in culinary aspects, so they fetch a high price to end up on the dinner menu. They've also suffered from bacterial infections that leave them unable to attach to hard surfaces. Many abalone species are endangered to extinction.

Abalones use tentacles on a extending piece of their foot, that's the muscle they use to move around and cling to surfaces, to sense the environment around them. If touched by a sea star, an abalone will whip its shell around to dislodge the predator. Other threats to these animals include octopuses, wrasses, sharks and rays, shore birds, and more. Their large, protective shell, however, helps defend them. Like a limpet, when an abalone grabs hold of the substrate, it's almost impossible to remove. 

Something noticeably unique about these snails is that their shell actually has holes in it! This is by design. The holes in an abalone's shell are used for gamete and waste disposal as well as water flow over their gills. The holes help them poop and help them breathe!

For more facts on abalones, 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!