Tag Archives: red handfish

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, but there are lots of species in many genera in the family Stomiidae. Many have barbels with photophores at the end that lure prey, and most have long needle-like teeth and jaws that can open incredibly wide. They also have stretchy stomachs so they can hold whatever they manage to catch. As you may have guessed from these traits, the dragon fish lives in the deep sea where there’s little or no light from the surface.

You may wonder why deep-sea fish even have eyes if there’s no light. Fish that live in cave systems eventually evolve to be eyeless, since they don’t need their eyes to see and growing eyes is just a waste of their energy. It’s because even though there’s no sunlight in the deep sea, there is light from lots of different organisms. Many, many deep-sea animals produce bioluminescent light to attract mates or trick smaller animals into coming closer.

Any sunlight that does find its way to the depths of the ocean is blue, because blue has the shortest wavelength and can travel farther. Red wavelengths are longest so that red is the first color lost when you start descending into the water. One article that I’ve linked to in the show notes mentions that if a diver gets a cut, the blood looks brown or even black if the water is deep enough. That’s creepy.

As a result, deep-sea fish are most sensitive to the color blue. Most of them can’t perceive red at all because there just isn’t any red in their environment. And that’s where the dragon fish comes in, because some species of dragon fish can not only see red, they produce red light that illuminates everything around them. A fish or other animal swimming along has no idea that it’s lit up like it’s under a red spotlight because it can’t even see that color.

At least one species, the black dragon fish, perceives red light very differently from the way other animals do. As far as we know it’s unique among all animals. Its eyes contain a photosensitizer derived from chlorophyll, which allows it to see shorter lightwaves. Chlorophyll is found in plants and some bacteria, and it’s actually a specialized pigment that absorbs energy from light. It’s the reason why plants are green. But the black dragonfish uses the chlorophyll it digests to perceive red light.

But remember how dragon fish have giant sharp fangs and will eat pretty much anything they can swallow? Where does the black dragon fish get the chlorophyll it needs? There aren’t any plants in the deep sea anyway.

The answer seems to be that the black dragon fish eats a whole lot of copepods, tiny crustaceans that live throughout the world. The particular species of copepods that the black dragon fish prefers contain a type of chlorophyll.

Finally, Cosmo wanted to learn about the freshwater stingray. We talked about it in episode 296, but mostly we concentrated on the South American fish in that episode. There are freshwater stingrays that live in other parts of the world, such as Asia. This includes the white-edge freshwater whipray, which is extremely rare and only found in four rivers in Southeast Asia.

The white-edge freshwater whipray grows up to two feet across, or 60 cm, with a thin tail about two and a half times longer than the body itself so that technically it can grow around 6 and a half feet long, or 2 meters. Most of that length is tail, though. It’s mostly brown so it can hide in the sandy mud at the bottom of the river, with black dermal denticles down the middle of its back. The tail is mostly white, though, and has two long stinging spines that can be over 3 inches long, or 8 cm.

While the white-edged whipray lives in rivers, it can also tolerate brackish water where the ocean and the river waters mix. It eats small animals it finds on the bottom of the river, including crustaceans and mollusks. It’s endangered due to habitat loss, overfishing, and pollution.

The white-edged whipray is so rare these days that it’s unlikely that anyone would accidentally step on one in the water. But if they did, the ray would whip its long tail up and jab the spines into the person’s leg or foot. The spines can do a lot of damage on their own, but the venom they inject makes the wound incredibly painful and can even potentially kill the person.

If you plan to do some wading in a South Asian river anytime soon, make sure to shuffle your feet as you walk to scare away any potential whiprays before you step right on it.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

 

Episode 189: The Handfish and the Lumpsucker

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This week we have two more listener suggestions, so thanks to Rosy and Simon! They both suggested small but intensely interesting fish!

Further reading:

The Handfish Conservation Project – Name a Fish!

Further watching:

Pacific Spiny Lumpsucker making adorable faces

The only smooth handfish specimen in the whole world:

In case you were wondering why it’s called a handfish (this one is a spotted handfish):

A red handfish. You’d be angry too if there were fewer than 100 individuals left in your species (photo by Rick Stuart-Smith):

A Pacific spiny lumpsucker:

HOW IS THIS REAL? I AM GOING TO DIE. These are real lumpsuckers on a real balloon in an aquarium. Apparently it’s a birthday party thing to do in Japan:

The sucker part of the lumpsucker:

SO ANGY:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’re going to learn about two interesting fish, but first a CORRECTION!

In the hyena episode last week I called the hyena a canid, and it’s not! Yikes, that was a major blunder on my part. Thanks to Bal for the correction. Hyenas aren’t even very closely related to canids at all. They’re in the family Hyaenidae while canids are in the family Canidae, although both are in the order Carnivora along with cats and walruses and raccoons and weasels, etc. AND thanks to Simon who also let me know that the striped hyena lives in the Middle East and Asia as well as Africa. Sorry, y’all. I hate when I make mistakes.

Anyway, back to the fish! We’ll start with the handfish, which happens to be a suggestion by Simon. Simon sent me an article about the smooth handfish specifically, and it’s a sad article because the smooth handfish has been declared extinct.

The smooth handfish used to be a common fish that lived off the coast of Tasmania in warm, shallow water. It was reddish-brown with darker brown markings, and it grew to about 1 3/4 inches long, or 4.4 cm. But the area where it lived was dredged so intensively for oysters and scallops up until 1967 that the fish’s habitat was destroyed. It was described in 1802 from a single specimen caught by a French naturalist, but that’s the only smooth handfish anyone ever bothered to collect for science. And now it’s the only specimen we have to study.

The reason the smooth handfish was so vulnerable to habitat loss is that it didn’t have a larval stage where newly hatched fish could disperse to new areas by floating on currents. Handfish eggs hatch into teeny baby handfish, not larval handfish. As a result, it was restricted to only specific areas and when those areas were destroyed by dredging, the fish was driven extinct. And the really awful thing is, the only reason people stopped dredging for oysters and scallops is because they’d been so overfished that there basically weren’t any left. The smooth handfish is actually the first marine fish known that has gone extinct in modern times.

There are 13 other species of handfish known in the world, but they’re all endangered due to pollution, habitat loss, and the spread of invasive species. Like the smooth handfish, other handfish species lay eggs that hatch into juvenile fish instead of larval fish, so they’re also especially vulnerable to habitat loss. For example, there are fewer than 100 red handfish alive in two small areas off the coast of Tasmania. We know because each fish has unique markings, which allows conservationists to identify individuals. A group called the Handfish Conservation Project has put together a database of living individuals, and if you donate at least $1,000 (in Australian dollars) you get to give one of the fish a name. I’ll put a link in the show notes so you can go look at the fish and see the names some of them have been given. The names include Ginger Ninja, Knuckles, Rosie Palm, and The Stalker.

The handfish is called that because its pectoral fins look like big flat hands that it uses to walk along the ocean floor. It’s actually related to the anglerfish, and like anglerfish it has an illicium above its mouth. Anglerfish use the illicium as a lure to attract animals that it then gulps down, but the handfish’s illicium is relatively small and researchers aren’t sure if all species use it as a lure. We’re not even completely sure what handfish eat, although there are reports of handfish eating polychaete worms, small fish, and crustaceans like amphipods and shrimp.

All the species live off the coast of Australia, especially around Tasmania. The largest species only grows to about 6 inches long, or 15 cm.

That is pretty much all we know about the handfish, so let’s move on to our other fish today, a suggestion by Rosy. Rosy wants us to talk about the lumpsucker, and I cannot argue with this because they are weirdly adorable fish.

The lumpsucker lives in cold waters near the Arctic. Most species live in the North Pacific but some also live in the North Atlantic. It doesn’t swim very well and, like the handfish, it spends most of its time on the sea floor. But unlike the handfish, which lives in shallow coastal water, some lumpsuckers live in the deep sea, up to 5,600 feet deep, or 1,700 meters. It eats small crustaceans, mollusks, polychaete worms, and other small animals, and the deep-sea species may also eat small jellyfish.

There are around 30 species of lumpsucker known, and we don’t know a whole lot about most of them. Most are small, but the biggest can grow 20 inches long, or 50 cm, and weigh as much as 11 lbs, or 5 kg. That’s Cyclopterus lumpus, which varies in color from blue or gray to yellowish or brown, and sometimes greenish, although during breeding season males turn orangey-red. The female’s eggs are eaten by people as imitation caviar, and it’s the only lumpsucker that is fished for as a result. Some people eat the fish itself too, especially in Iceland, but usually only the males. The females reportedly taste bad.

Cyclopterus lumpus has become a helpful addition to salmon farming in a surprising way. It eats parasites called sea lice, which infest the salmon. The lumpsuckers do such a good job cleaning the salmon of sea lice that fish farmers don’t have to use parasiticides.

The lumpsucker gets its name because it’s a little round lump of a fish and it has modified pelvic fins that act as a little sucker on its belly that lets it stick to things. The lumpsucker also has little hard bumps on its body. It has big round eyes and a little round mouth. Basically what I’m trying to say is the best word to describe a lumpsucker is ROUND. So round.

The lumpsucker doesn’t have a swim bladder. Instead, it has jelly-like fat deposits that increase its buoyancy. The female lays her eggs in rock crevices and the male stays to guard the eggs. He uses his tail and tiny fins to push water over the eggs so they stay aerated, and remains with them until they hatch several weeks later. The larvae are well developed and already have suckers.

Probably the most well-loved species of lumpsucker is the Pacific spiny lumpsucker, which is the roundest and most adorable, and is often kept in aquariums. It grows to about three inches long, or 7.5 cm, and it varies in color. Females are usually greenish while males are orange or reddish, but individuals can be gray, brown, or yellow too. In the wild it lives around Japan, northern California, and many other areas, where it spends most of its time stuck to pieces of eel grass, kelp, or rocks, making adorable faces at things. There’s a link in the show notes to a little video of one sticking itself to a rock, looking around, moving slightly with its teeny fins, sticking itself back to the rock… You really need to watch it. It will make you feel very calm.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, or if you have a great idea for a red handfish name, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us that way.

Thanks for listening!