Episode 130: Strangest Small Fish

Published: July 29, 2019, 7 a.m.

b"This week we're going to revisit a suggestion from Damian and follow up on episode 96, our strangest big fish episode. This time let's find out about some weird small fish!\\n\\nThe teeny, newly-discovered American pocket shark:\\n\\n\\n\\nThe brownsnout spookfish wears its mirror sunglasses on the INSIDE:\\n\\n\\n\\nThe goblinfish with a dangerous head and basically a dangerous everything else too:\\n\\n\\n\\nTwo teeny pygmy seahorses. Can you spot them? Hint: they're the ones with eyes.\\n\\n\\n\\nThe razorfish. Just another sea urchin spine, no fish to see here:\\n\\n\\n\\nThe much-maligned candiru:\\n\\n\\n\\nThe red-lipped batfish:\\n\\n\\n\\nGimme kiss:\\n\\n\\n\\nShow transcript:\\n\\nWelcome to Strange Animals Podcast. I\\u2019m your host, Kate Shaw.\\n\\nAges ago, Damian suggested an episode about weird fish. We covered some weird big fish in episode 96, but now it\\u2019s time for some weird little fish.\\n\\nSo, think about sharks for a second. Big, scary, sharp teeth, fast swimmers, black eyes of a pitiless killer of the deep.\\n\\nBut have you perhaps considered that maybe the world needs a very small shark? One that actually kind of looks like a tiny whale? Like, a tiny shark, only about 5 \\xbd inches long, or 14 cm. Almost, you know, pocket sized. Oh, and it should glow in the dark.\\n\\nThat\\u2019s the American pocket shark, a real animal that was only discovered in 2010! It\\u2019s called a pocket shark not because it\\u2019s pocket sized, although it is, but because it has a sort of pocket on each side near its gills that produces luminous fluid. Researchers aren\\u2019t sure whether the shark uses the fluid for attracting prey or avoiding predators. Maybe both. Its head is bulbous and rounded, which kind of makes it look like a tiny whale.\\n\\nThe American pocket shark was discovered in the Gulf of Mexico while scientists were observing sperm whales and tracking them with sonar. When a whale surfaced from a dive, the research team dropped nets to the depth the whale had dived to, hoping to catch the same kind of prey the whales were eating. And one of the things they found in the net was a tiny shark new to science, found at a depth of 3,000 feet, or 914 meters.\\n\\nIn 2013 the tiny shark, which had been frozen for later study, was finally examined. The expert who looked at it had only seen one other shark like it before, a shark discovered in the eastern Pacific in 1979. But this tiny shark had some differences from that tiny shark, and after examining both specimens carefully, they\\u2019ve been classified as different species.\\n\\nSo that\\u2019s a cute start, but it\\u2019s still just a rare little shark that glows. Not really that unusual, right? Let\\u2019s look at a really weird fish next. Like, seriously weird.\\n\\nIt\\u2019s called the brownsnout spookfish, which is a really terrible name, but it\\u2019s not a terrible fish. I mean, it couldn\\u2019t hurt you. It grows about 7 inches long, or 18 cm, and eats copepods and other tiny crustaceans. Its snout is long and kind of pointy, its body is slender, and it has elongated pelvic fins. Because it lives in the deep sea, it has eyes that point upward, which help it see predators and prey that might be silhouetted against the far-distant surface of the ocean. But it also has something only one other fish is known to have, an extra structure to the side of the eyeball. It\\u2019s called a diverticulum and it does two things. First, it allows the fish to see downward in addition to upward, and second, it allows it to see across a really wide angle. The diverticulum does this because it contains a mirror that reflects light from the main eyeball onto the retina of the diverticulum. A MIRROR IN ITS EYEBALLS. The mirror is made up of tiny crystalline plates.\\n\\nSome invertebrates like clams and crustaceans contain reflectors in their eyes, but except for the brownsnout spookfish, the only other vertebrate known to have mirrored eyeballs is the glasshead barreleye. Also a terrible name. The glasshead barreleye is a little smaller than the brownsnout spookfish, and not surprisingly,"