Tag Archives: salmon

Episode 455: Spooky Animals

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Thanks to Richard of NC, Richard my brother, Siya, Ezra, and Owen and Aksel for their suggestions this week!

Further reading:

Creature Feature: Googly-Eyed Stubby Squid

Nocturnal Spiders Use Trapped Fireflies as Glowing Bait to Attract Additional Prey

A male vampire deer:

The adorable googly eyed squid [still taken from video linked above]:

The snowy owl [photo by Bill Bouton from San Luis Obispo, CA, USA – Snowy Owl, Bubo scandiacus, male, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=19899431]:

Show transcript:

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

This week for monster month, let’s learn about some animals that are considered spooky, although in actuality they’re just regular animals who don’t even know the meaning of spooky. Thanks to Ezra, Owen and Aksel, Richard from NC, my brother Richard, and Siya for their suggestions!

We’ll start with the two Richards. Richard from NC suggested vampire deer, and my brother Richard suggested zombie salmon.

The vampire deer is more commonly called the water deer, but considering it has tusks growing down from its upper jaw that look like fangs, vampire deer is an excellent name. Females have short tusks, but in males they grow quite long, sometimes over 3 inches long, or 8 cm. Since the animal only stands about two feet tall at the shoulder, or 65 cm, that’s pretty impressive. Its hind legs are longer than its front, so that when it runs it sort of bounces like a rabbit. It has a very short tail, small rounded ears, and is golden brown in color with a lighter underside. It doesn’t have antlers. We talked about the musk deer in episode 366, which also has fangs instead of antlers, but the vampire deer isn’t closely related to the musk deer.

The vampire deer currently lives in Korea, China, and Russia although it used to be much more widespread. It mostly lives in reedy habitats near rivers, and it’s a solitary animal although females will sometimes congregate to eat. Males protect their territories by fighting with their tusks, although they don’t actually drink blood.

As for the zombie salmon, it’s not a type of fish but something that can happen to an ordinary salmon. The salmon is a fish that famously spends most of its adult life in the ocean, but travels up rivers to spawn. The eggs hatch in freshwater and the baby fish grow up in the river, and then they migrate to the ocean and live there for almost the rest of their lives. Eventually the fish is fully mature and ready to spawn, so it travels to the river where it was hatched, fights its way upstream, and the cycle starts all over with the new generation.

Almost all salmon die after spawning. This is partly because the energy requirements of swimming upstream is so high, but also because a salmon is genetically programmed to die after spawning. This is called senescence, and while it’s common in invertebrates like octopuses and some insects, it’s rare in vertebrates. Not only that, there’s not enough food for an adult salmon in the spawning area, and an adult salmon’s body is adapted for salt water, not fresh water, so it can’t live long in rivers as an adult anyway.

A small number of female Atlantic salmon are able to return to the ocean, recover and regain their strength, and spawn again a few years later, but for all other species, after spawning, that’s it. Within days all the salmon have died.

But sometimes, rarely, a salmon remains alive for weeks after spawning. It doesn’t have the energy to return to the ocean, and its body is in the process of shutting down for planned senescence, and the freshwater is causing damage to the fish’s skin. But still it survives, growing more and more raggedy, just like a zombie in a movie. But unlike movie zombies, it doesn’t want to eat brains. Eventually the zombie salmon dies, if something doesn’t catch and eat it first.

Next, Siya suggested the googly-eyed squid. Some people find squid and octopuses scary because they look so strange, but I admit I added this squid to the episode because I think its name is funny. It’s also called the stubby squid or the googly-eyed stubby squid. Its scientific name is Rossia pacifica, which gives you a hint that it lives in the northern Pacific Ocean. In the winter it likes shallow water without strong currents, but in summer it migrates to deeper water where it doesn’t get too warm.

The googly-eyed squid is small and closely related to the cuttlefish. It grows less than four and a half inches long, or 11 cm, including its eight short arms and two retractable tentacles. It’s usually reddish-brown or purplish in color, but like most squid it can change color when it needs to. It gets its name because it has large eyes that show white around the edges and have a black pupil, which makes it look like it has googly eyes.

During the day, the googly-eyed squid buries itself most of the way in sand or mud at the bottom of the sea floor, with just its googly eyes showing so it can watch for danger. At night it comes out to hunt small animals like crabs and other crustaceans, mollusks, and fish, but what it really likes is shrimp. Naturally, it has good eyesight.

Next, let’s talk about a bird that some people find spooky. Ezra, Owen, and Aksel all suggested the snowy owl.

The snowy owl is mostly snow-white although young birds have black and gray markings. Its eyes are yellow and it often hunts in the daytime, but not always. Its wingspan can be as much as six feet across, or 1.8 meters.

The snowy owl lives throughout the Arctic and nearby regions, especially in summer, but sometimes travels long distances to find food. It’s also migratory, traveling south for the winter. Snowy owls have been spotted in such far-flung places as Hawaii, Bermuda, Pakistan and India, Iran, and Japan and Korea.

The snowy owl mostly eats small animals like lemmings and mice, although it will kill and eat pretty much anything it can catch, including ducks and other water birds, fish, and even insects and frogs. It will sometimes eat carrion and even sometimes steals food from other birds. It swallows small animals whole, and a day or two later, regurgitates a compacted pellet made up of the indigestible parts, including bones and fur. A lot of predatory birds do this, not just snowy owls. Scientists who study the birds love finding these pellets, because they can dissect them and learn what the bird has been eating.

Not only does the snowy owl make its nest on the ground, sometimes it hunts on the ground too, just running along after an animal on its big feet.

This is what the snowy owl sounds like:

[owl call]

Let’s finish with an invertebrate that a lot of people are scared of, a spider! This particular spider is a species of sheet-web spider, which lives in Taiwan. It’s a nocturnal spider that was only described in 2012. Unlike a lot of spiders, which build upright webs to trap insects that are flying along between branches and twigs, the sheet-web spider builds its web horizontally just above the ground.

The webs are light-colored and reflect light. The spiders build their webs in shady areas, and scientists think that moths see the light reflecting off the webs, and think the webs are actually the ground in an area open to the sky. Moths like open areas like this, and moths also happen to be one of the spider’s favorite foods. When a group of scientists experimented by darkening some webs with charcoal dust, they determined that the darkened webs attracted considerably fewer moths.

But it turns out that the sheet-web spider does something even more extraordinary. If a firefly gets caught in the web, the spider doesn’t eat it—or at least, not right away. It lets it stay in the web, flashing its light. Scientists noticed this and were intrigued. Did the fireflies not taste good, or was something else going on?

They placed LEDs that blinked like fireflies in some webs, but not in others, and monitored the results. It turns out that three times the number of insects were attracted to the webs with fake fireflies, and most of those were other fireflies. Fireflies attract a mate by flashing. The spiders were taking advantage of having a built-in lure stuck in their webs. So even though spiders are very tiny and have tiny brains, sometimes they’re pretty darn smart.

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 340: Whale Lice and Sea Lice

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Thanks to Eilee for suggesting the sea louse this week!

Further reading:

Secrets of the Whale Riders: Crablike ‘Whale Lice’ Show How Endangered Cetaceans Evolved

Parasite of the Day: Neocyamus physeteris

A whale louse [By © Hans Hillewaert, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=19259257]:

The salmon sea louse [By Thomas Bjørkan – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7524020]:

Show transcript:

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

It’s now officially August, so we’re officially kicking off Invertebrate August with two invertebrates with the word louse in their names, even though neither of them are technically lice. Thanks to Eilee for suggesting sea lice, and thanks to our patrons because I used some information from an old Patreon episode for the first part of this episode.

That would be the whale louse. The whale louse isn’t actually a louse, although it is a parasite. Lice are insects adapted for a parasitic lifestyle on the bodies of their hosts, but whale lice are crustaceans—specifically, amphipods specialized to live on whales, dolphins, and porpoises.

There are many species of whale louse, with some only living on a particular species of whale. In the case of the sperm whale, one species of whale louse lives on the male sperm whale while a totally different species of whale louse lives on the female sperm whale and on calves. This was a fact I found on Wikipedia and included in the Patreon episode, but at the time I couldn’t find out more. It’s puzzled me ever since, which is one of the reasons I wanted to revisit this topic. I couldn’t figure out how the male calves ended up with male sperm whale lice, and I couldn’t figure out why males and females would have different species of lice. I’m happy to report that I now know the answers to both questions, or at least I can report what experts hypothesize.

Male sperm whales spend more time in polar waters while females spend more time in warmer waters to raise their calves. Sperm whales are actually host to three different whale lice species, but one species prefers colder water and is much more likely to live on males, while another species prefers warmer water and is much more likely to live on females and calves. Any sperm whale might have lice from any of the three species, though, and whale lice are spread when whales rub against each other. This happens when the whales mate, but it also happens when males fight or when whales are just being friendly.

The whale louse has a flattened body and legs that end in claws that help it cling to the whale. Different species are different sizes, from only five millimeters up to an inch long, or about 25 mm. Typically the lice cling to areas where water currents won’t sweep them away, including around the eyes and genital folds, ventral pleats, blowholes, and in wounds. Barnacles also grow on some whales and the lice live around the barnacles. But even though all that sounds horrible, the lice don’t actually harm the whales. They eat dead skin cells and algae, which helps keep wounds clean and reduces the risk of infection.

The right whale is a baleen whale that can grow up to 65 feet long, or almost 20 meters. Right whales have callosities on their heads, which are raised patches of thickened, bumpy skin. Every whale has a different pattern of callosities. Right whales are dark in color, but while the callosities are generally paler than the surrounding skin, they appear white because that’s where the whale lice live, and the lice are white. This allows whales to identify other whales by sight. It’s gross but it works for the whales. Right whales also usually host one or two other species of louse that don’t live on the callosities.

Dolphins typically have very few lice, since most dolphins are much faster and more streamlined than whales and the lice have a harder time not getting washed off. Some dolphins studied have no lice at all, and others have less than a dozen. Almost all whales have lice.

Scientists study whale lice to learn more about whales, including how populations of whales overlap during migration. Studies of the lice on right whales helped researchers determine when the whales split into three species. But sometimes what researchers learn from the lice is puzzling. In 2004 researchers found a dead southern right whale calf and examined it, and were surprised to find it had humpback whale lice, not southern right whale lice. Researchers hypothesize that something had happened to the calf’s birth mother and it was adopted by a humpback whale mother. Another study determined that a single southern right whale crossed the equator between one and two million years ago and joined up with right whales in the North Pacific. Ordinarily right whales can’t cross the equator, since their blubber is too thick and they overheat in warm water. Researchers suggest that the right whale in question was an adventurous juvenile who crossed in an unusually cool year. The lice that whale carried interbred with lice the North Pacific whales carried, leaving a genetic marker to tell us about the whale’s successful adventure.

Some animals do eat whale lice, including a little fish called topsmelt. Topsmelt live in shallow water along the Pacific coast of North America. It grows up to around 14 inches long, or 37 cm, and has tiny sharp teeth that it uses to eat zooplankton. But in mid-winter through spring, gray whales arrive in the warm, shallow waters where the topsmelt live to give birth. Then schools of topsmelt will gather around the whales, eating lice and barnacles from the whale’s skin. Good for those little fish. That makes me feel better for the whales.

Eilee suggested the sea louse a while back, and when I looked it up initially I was horrified. Sea lice is another name for a skin condition called seabather’s eruption that consists of intense itching and welts on the skin, that occurs after someone has been swimming in some parts of the world. That includes around parts of New Zealand, off the coast of Queensland, Australia, off the eastern coast of Africa, parts of south Asia, the Caribbean and Gulf of Mexico, and many other places. It usually shows up a few hours after a swimmer gets out of the water, and since it almost always shows up in people who keep wearing their bathing suit for a while after swimming, or wear their suit into a shower to rinse off, people used to think the itching was due to a type of louse that got caught in the suit. They were half-right, because it is due to a microscopic animal that gets trapped against a person’s skin by their bathing suit. It isn’t a louse, though, but the larvae of some species of jellyfish. The larvae aren’t dangerous to humans or anything else, but they do each have a single undeveloped nematocyst. That’s a stinging cell, the same kind that adult jellyfish have. In the case of the larvae, the sting only activates when a larva dies, and it dies if it dries out or gets soaked in fresh water. Fortunately, seabather’s eruption isn’t a very common occurrence and while it’s uncomfortable for a few days, it’s not dangerous and can be treated with anti-itch cream.

There is a type of animal called the sea louse, of course, but it doesn’t want anything to do with humans and wouldn’t bite a human even if it could. It’s a parasitic crustacean like the whale louse, but it only lives on fish. It’s also not related to the whale louse and doesn’t look anything like the whale louse. The whale louse looks kind of like a flattened shrimp without a tail, while the sea louse is hard to describe. It has a flattened shield at the front, with a thinner tail-like section behind, although it’s actually not a tail but the louse’s abdomen. Its legs are underneath its body and are short and hooked so it can keep hold of its host fish, although the shape of its shield acts as a sort of suction cup that also helps it remain attached.

Like the whale louse, different species of sea louse live on different species of fish. It’s usually quite small, less than 10 mm long, although at least one species can grow twice that length. Males are much smaller than females. It eats the mucus, skin, and blood of its host fish, and its mouthparts form a sharp cone that it uses to stab the fish and suck fluids out. Naturally, this isn’t good for the fish.

Most of the time a fish only has a few sea lice, if any, but sometimes when conditions are right a fish can have a much heavier infestation. This can lead to the fish dying in really bad cases, sometimes due to diseases spread by the lice, infected wounds caused by the lice, or just from anemia if the lice drink too much of the fish’s blood.

Conditions are right to spread sea lice when fish are crowded in a small space, and this happens a lot in farmed fish. It’s especially bad in salmon, so while we don’t know a lot about most sea lice, we know a whole lot about the species of sea louse that parasitizes salmon. It’s called Lepeophtheirus salmonis and it’s the sea louse that grows bigger than most others. Salmon are big fish, with the largest growing over 6 ½ feet long, or 2 meters.

The salmon sea louse has a complicated life cycle and only lives on fish part of the time, which is probably true of all sea lice. The female louse develops a pair of egg strings that hang down from the rear of her body, and each string has around 150 eggs. The eggs hatch into tiny larvae that mostly just drift along through the water, although they can swim. A larva molts its exoskeleton every few days as it transforms into new stages of development, and all the time it’s looking for a host fish.

Once it finds a salmon, the sea louse grabs hold and stays put until it molts again and reaches the next stage of its development, which doesn’t take long. Then it’s able to walk around on the fish and it can swim too if it needs to.

The sea louse can’t survive very long in fresh water, but that’s weird if you know anything about salmon. Salmon are famous for migrating from the ocean into rivers to spawn, and after spawning, most adult salmon die. Some Atlantic salmon will survive and return to the ocean, but most salmon die within a few days or weeks of spawning. Because all the sea lice die once the salmon enter fresh water, the new generation of salmon don’t get sea lice until they make their way into the ocean.

That’s a natural way that sea lice populations are kept under control. The salmon sea louse will also live on a few other species of fish, including the sea trout. But people like eating salmon, and farming salmon is an important industry. Unfortunately, as I mentioned earlier, having lots of fish in one place means the sea louse can also increase in numbers easily.

Salmon farmers have tried all kinds of things to get rid of sea lice, from underwater lasers that zap the lice to kill them, to putting cleaner fish among the salmon to eat the lice. Scientists are even trying to breed a variety of salmon that’s much more resistant to sea lice infestation, although this is controversial since it makes use of genetic modification. Not all countries allow genetically modified fish to be sold as human food.

For the most part, though, wild fish generally don’t have a lot of sea lice—and if they do, they can just visit a cleaner fish. Thank goodness for cleaner fish!

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. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. 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!