• Episode 397: Some Colorful Fishies

  • Sep 9 2024
  • Length: 11 mins
  • Podcast

Episode 397: Some Colorful Fishies

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  • Thanks to Cosmo, William, and Silas for their fishy suggestions this week! You have until Sept. 13, 2024 to back the enamel pin Kickstarter! Further reading: The Handfish Conservation Project Researchers Look in Tank and See Promising Cluster of Near-Extinct Babies The unique visual systems of deep sea fish A red handfish: Another red handfish. This one is named Hector: The black dragon fish: The white-edged freshwater whipray [photo by Doni Susanto]: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. This week we return to the vertebrate world, specifically some strange and colorful fishies. Thanks to William, Cosmo, and Silas for their suggestions! We’ll start with Silas’s suggestion, the red handfish. We talked about it before back in episode 189, but it’s definitely time to revisit it. When we last discussed it, scientists estimated there were fewer than 100 red handfish left in the wild, meaning it was in imminent danger of extinction. Let’s find out how it’s doing now, four years later. The handfish gets its name because its pectoral fins look like big flat hands. It spends most of its time on the sea floor, and it uses its hands to walk instead of swimming. It can swim, although it’s not a very strong swimmer, and anyway if you had great big hands you might choose to walk on them too. It doesn’t have a swim bladder, which helps most fish stay buoyant. All species of handfish are small, only growing to about 6 inches long at most, or 15 cm. This is surprising considering the handfish is closely related to anglerfish, and some anglerfish can grow over 3 feet long, or about a meter. As for the red handfish specifically, it generally only grows about 4 inches long at most, or 10 cm, and it once lived in shallow water around much of Australia. These days, it’s only found on two reefs southeast of Tasmania. Some populations are bright red while some are pink with red spots. It has a wide downturned mouth that makes it look like a grumpy red toad with big hands. So how is the red handfish doing? Four years ago it was almost extinct in wild, with fewer than 100 individuals alive. These days the Handfish Conservation Project estimates that the wild population is probably about the same, although because the red handfish is so small and hides so well among sea grass, algae, and rocks that make up its home, it’s hard to get a good count of how many are really alive. It’s also under even more pressure than before as an overpopulation of urchins is overgrazing the plants where it lives, which may sound familiar to you if you listened to episode 395 a few weeks ago. But there is one fantastic change that gives conservationists hope that the red handfish won’t go extinct after all. The red handfish is so endangered, and its remaining habitat is so small, that a few years ago scientists decided they needed to start a captive breeding program. But even though the fish did just fine in captivity, they didn’t breed at first. Then, in November 2023, one of the fish laid 21 eggs and all 21 hatched safely. Hopefully it won’t be long until the babies are old enough to release into the wild. The red handfish is one of very few fish that hatch into tiny baby fish instead of into a larval form. Newly hatched babies are only about 5 mm long. Most fish colonize new habitats after they float around aimlessly as larvae, until they grow enough to metamorphose into adults. Since the red handfish doesn’t have this larval stage, and babies just walk around on the sea floor finding tiny worms and other food, it’s hard for the fish to expand its range. Hopefully, as the captive breeding program continues and more young fish are released into the wild, scientists can start releasing red handfish into areas where they used to live. Next, William asked about the dragon fish. We’ve talked about a few dragonfish before, in episodes 193 and 231,
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