Episode 359: The Antarctic Death Star(fish)!
b'Thanks to Morgan for suggesting this week\'s topic, the Antarctic Death Star!\\n\\nFurther reading:\\n\\nGiant Monster Starfish ALERT\\n\\nEchinoderm Tube Feet Don\'t Suck! They Stick!\\n\\nBodies of Starfish and Other Echinoderms Are Really Just Heads, New Research Suggests\\n\\nThe Antarctic death star [from first link listed above]:\\n\\n\\n\\nThe "beartrap" structures, magnified [from first link listed above]:\\n\\n\\n\\nShow transcript:\\nWelcome to Strange Animals Podcast. I\\u2019m your host, Kate Shaw.\\nIt\\u2019s been way too long since we talked about an invertebrate, so this week we\\u2019ll look at one suggested by Morgan, the Antarctic death star.\\nIt has a lot of other names too, including the Antarctic sun starfish and the wolftrap or beartrap starfish. Its scientific name is Labidiaster annulatus. I\\u2019m going to call it the death star because I think that\\u2019s hilarious.\\nAs you may have guessed from its common names, the Antarctic death star is a starfish that lives in cold ocean waters near the Antarctic, AKA the south pole. But its common names also hint at how it gets its food, and this would be a good time to take a moment and be glad you\\u2019re not a copepod that also lives in the Antarctic Ocean.\\nThe death star is reddish-brown on its dorsal side, white underneath. It\\u2019s a large starfish, up to two feet across, or 60 cm, and it also has a lot of legs, more properly called rays\\u2014up to 50 of them. The rays are long, narrow, and very flexible, and the undersides have rows of little structures called tube feet. All echinoderms, including starfish, have these tube feet and they\\u2019re used for several purposes. One important purpose is helping the animal stick to a hard surface, which allows it to climb around more easily and right itself if it gets flipped over.\\nFor over 150 years scientists thought the tube feet acted like little suction cups, but that didn\\u2019t explain how a starfish or other echinoderm could stick to porous surfaces. It wasn\\u2019t until 2012 that a study was published explaining how the tube feet actually work. The tube feet exude tiny amounts of a sticky chemical that acts like glue.\\nThe death star\\u2019s body also has little spines and bumps all over it, but it also has some structures that give the animal its other names, the wolftrap or beartrap starfish. The structures are called pedicellariae [PED-uh-suh-LAIR-ee-aye], which are also common in echinoderms. Most echinoderms seem to use them to keep algae and other organisms from settling on the body, although scientists aren\\u2019t completely sure. Pedicellariae have muscles and sensory receptors, and when something touches them, they snap shut like a trap. In the case of the Antarctic death star, its pedicellariae are extra big and really sharp. When a krill or other tiny animal brushes against one of these little traps, it grabs the animal and then the death star can eat it.\\nBut that\\u2019s just part of what\\u2019s going on when the death star goes hunting, so let\\u2019s discuss it in more detail.\\nMost starfish spend almost all their time on the ocean floor, walking around looking for food. The death star does this too, but not all the time. Quite often a death star will climb on top of a rock or other large structure, and then it will extend some of its rays up and out into the water. It waves its rays around and if it touches a small animal, it will wrap the rays around it. The pedicellariae also snap shut. Then the death star can eat whatever it caught. Usually this is krill or amphipods, but it\\u2019s not a picky eater. Since it will eat animals it finds already dead, researchers aren\\u2019t completely sure if the death star ever catches fish. They\\u2019ve certainly found dead fish in death star stomachs, but the water it lives in is so cold that not many fish live there anyway. Fish don\\u2019t make up a big part of the death star\\u2019s diet, whether or not it\\u2019s catching them itself. The death star also eats other starfish, including smaller death stars.\\nLike other starfish, the death star can eat surprisingly large pieces of f...'