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It's INVERTEBRATE AUGUST! Thanks to Elizabeth, Richard, and Llewelly for their suggestions this week!

Further reading:

Meet Phylliroe: the sea slug that looks and swims like a fish

Hey, so these sea slugs decapitate themselves and grow new bodies

Found, Then Lost, Then Found Again: Scientists Have Rediscovered the Sand Octopus

A sand crab in the air:



Sand crabs in the water, feeding:



Phylliroe is a sea slug that looks like a fish (pictures from article linked to above):



How I used to draw snails when I was a kid, adding an extra foot because I didn't understand that the "foot" of a snail/slug is the flat part of the body that touches the ground:



The mysterious sand octopus in mid-swim:



Show transcript:
Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.
It’s the first week of invertebrate August and we’re heading to the ocean for our first episode! Let’s jump right in with an episode about sand crabs, a couple of sea slugs, and an octopus mystery that was recently solved. Thanks to Elizabeth, my brother Richard, and Llewelly for their suggestions!
We’ll start with Elizabeth’s suggestion. The sand crab is also called the sand bug, the mole crab, or similar names that refer to its habit of burrowing into the sand. It’s common throughout much of the world’s oceans, especially in warm areas, and can be extremely numerous. It’s also sometimes called the sand flea, but it’s not the kind of tiny jumping crustacean that bites, also called the sand flea. This little crustacean is harmless to humans. It doesn’t even have pincers.
The sand crab isn’t a true crab although it is closely related to them. It’s gray-brown and has a tough carapace to protect it when it’s washed around by waves and to help protect it from predators. Females are larger than males and can grow up to an inch and a half long in the largest species, or about 35 mm, and an inch wide, or 25 mm. So it’s longer than it is wide, unlike most crabs, and its carapace is domed sort of like a tiny tortoise shell. Overall, it’s shaped sort of like a streamlined barrel. I saw one site that called it the sand cicada and it is actually about the same size and shape as a cicada, which it isn’t related to at all except that they’re both invertebrates. Some species have little spines on the carapace while others are smooth.
The sand crab lives in the ocean, specifically in the intertidal zone right at the area where waves wash up on the beach. This is called the swash, by the way, which is a great word. The sand crab burrows into the sand tail-first, using its strong rear legs, and during the time that there’s water over the sand, it unfurls its feathery antennae to filter tiny food particles from the water. When the wave goes out, it retracts its antennae and works on staying buried in the sand as the next wave rolls in.
In some species, males are very similar to females, but smaller. In other species, they’re tiny, barely 3 mm long at most, and even as adults they resemble larvae. The male finds a female and grabs hold of her leg, and there he stays. I tried to find out more about this, but it doesn’t look like the humble sand crab gets a lot of attention. If you’re interested in becoming a scientist who studies invertebrates and you want to spend a lot of time on the beach, the sand crab would make a good study buddy.
Lots of fish and birds eat sand crabs, and people do too. In many places they’re considered a delicacy and grilled as a snack. This isn’t surprising since they’re related to other crustaceans people like to eat, like crabs and lobsters.
Next, let’s learn about two strange sea slugs. We’ve talked about sea slugs a few times before, including in episodes 215 and 129, but there are a lot of species, with more being discovered pretty often.
Llewelly sent me a link ages ago about a sea slug that’s related to the sea bunn...