Horn Shark (Heterodontus francisci)

Don’t you think sharks with horns would be super cool? They’d reach a whole new level of badassery. Unfortunately, though today’s animal is called the horn shark, it does not actually have horns. People who name animals shouldn’t get my hopes up so much.

Horn sharks like warm waters, hanging around where temperatures are warmer than 20ºC. Their range is restricted to the eastern Pacific Ocean, and are particularly abundant along the coast of California and Mexico. These sharks live at the bottom of shallow waters, around 8-12 meters in depth. During winter they migrate into deeper waters, and can occasionally be found as deep as 200m, but this is rare.

Just because horn sharks don’t have actual horns, it doesn’t mean they don’t look cool. They have blunt noses, and a head that is capped by two ridges above the eyes (this is what gives them the ‘horn’ name). Horn sharks have two dorsal fins, in front of which are some neat and nasty spines. The sharks reach maximum lengths of around one meter, and are grey or brown with black spots covering the body.


A great picture of a horn shark, illustrating the animal’s ‘horns’. Image credit: Chad King via Wikipedia

Horn sharks are not great swimmers, and usually lie on the ocean floor, pushing themselves along the sand with their pectoral fins. They are nocturnal, coming out at night to feed on molluscs, sea urchins and crustaceans. Feeding on this type of prey can be troublesome; the hard shells of horn sharks’ prey can be quite difficult to break through. Horn sharks, though, have the highest bite force of any shark, relative to size. So chomping down on those shells isn’t too much of an issue for these guys.

The other problem horn sharks have with their diet is that often times molluscs and sea urchins attach themselves to rocks, making them difficult to pry off and eat. Horn sharks get around this with a peculiar method of feeding. They grab onto the prey and hold their head and pectoral fins along the ocean floor, and raise their tail as high as they can. They then bring their tail down, which forces the sharks’ heads up and pries the victim loose. It’s really incredible that horns sharks have figured out how to use themselves as levers.

Mating in horn sharks occurs in the winter, from December to January. Males swim after a female shark until she settles on the ocean floor, signalling her readiness to mate. The female lays eggs from February to April, laying eggs two at a time, for a maximum of 24. Once the eggs have been laid, the female shark grabs the case in her mouth, and places it in a rock crevice for protection. The egg cases of horn sharks are quite remarkable, having a double spiral around the outside to help secure it in these crevices. Young sharks are 15 cm long at hatching, and mature at 56-61 cm in length.


The egg case of a horn shark. Image credit: Devra via Wikipedia

Though horn sharks have scary spines that can inflict nasty wounds on people who get too close, these guys are pretty shy, and prefer to flee from people rather than bite. They are not usually caught for food purposes, but some divers will catch horn sharks to make jewelry out of their spines. Still, at the moment, horn sharks are not thought to be threatened, as they have little commercial value or threat to people. Seems like a pretty good survival strategy to me.

Cover image credit: Ed Bierman via Wikipedia

Four-eyed Fish (genus Anableps)

Yes, you read that right. Today’s animal is the family of fishes known as the four-eyed fish. I know this conjures images of fish wearing glasses (which is a hilarious thought), but these guys don’t wear glasses. Instead, they just have some very strange eye biology. Very strange.

There are only three species of four-eyed fish, the large-scale foureyes, the Pacific four-eyed fish, and the simply named foureyes. All species occur in a range spanning southern Mexico through Central America to the northern part of South America. The fish are found in brackish waters, usually in mangrove forests.

Four-eyed fish can grow to a maximum length of 32 cm, though they are usually smaller than that. They are pretty boring looking fish, being brown with a pale stripe running down each side of its body. But you didn’t click on this blog to read about what colour four-eyed fish are. You came here to find out about their eyes.

See how strange its eyes are? Image source: Wikipedia

See how strange its eyes are?
Image source: Wikipedia

So let’s get to it. Four-eyed fish don’t actually have four eyes, but what they do have is a pair of eyes that is split in two. Each eye has an above-water portion, and a below-water portion, with each having its own pupil. The top half of the eye is designed for seeing above water, while the lower half is best at seeing under water, with a thicker lens on the bottom to adjust for the different refractive index under water. Four-eyed fish sit just at the surface of the water, the top half of their eyes sticking into the air.

Another strange attribute of four-eyed fish is their reproductive behaviour. Both males and females have a ‘handedness’, a side on which they will mate. A right-handed male will only mate with a left-handed female, and vice versa. Four-eyed fish give birth to live young, keeping the eggs inside of them until they hatch.

An even weirder view of a four-eyed fish. Image source: http://www.practicalfishkeeping.co.uk/content.php?sid=4009

An even weirder view of a four-eyed fish.
Image source: http://www.practicalfishkeeping.co.uk/content.php?sid=4009

So although they don’t actually have four eyes, I think the four-eyed fishes definitely are right up there as some of the coolest fish around. After all, how many animals actually have split eyes?

Cover image source: https://quantumbiologist.wordpress.com/2011/04/26/four-eyes/

Puss Moth Caterpillar (Megalopyge opercularis)

I never really think of moths or caterpillars as being venomous. I’m not afraid of them, and I used to always pick up caterpillars as a kid. I think I even had a tupperware container with branches and leaves that I would keep caterpillars in. But apparently there are some species of these cute animals that are venomous, so be wary of them!

One species of venomous caterpillar is the puss caterpillar, which can be found in the southern US, Mexico, and in Central America. The adults are known by multiple names, including puss moth and southern flannel moth, but I will refer to them as puss moths since that’s what the larvae are generally known as, and they are the interesting facet of this species. They prefer to live on trees, usually oaks, elms and citrus trees. These nasty critters can also be found on rose bushes and ivy.

The adult puss moth. So very fuzzy.  Image credit: Patrick Coin via Wikipedia

The adult puss moth. So very fuzzy.
Image credit: Patrick Coin via Wikipedia

Despite the fact that they are venomous, puss caterpillars and moths are actually pretty cute. The caterpillars are covered in long silky ‘hairs’ that make them look a bit like tribbles. Colour of the caterpillars ranges from grey-white to brown to dark grey. Often caterpillars have an orange stripe running down the top of their bodies. The moths of this species are still very fuzzy, with hair all over their body and legs, and black fur on their feet.

Puss moths are not dangerous to people, but the caterpillars definitely are. The tricky thing about these guys is that they look soft and fluffy, which makes people want to pet them. This is a mistake, don’t do it. Hidden inside that floofy ‘fur’ are venomous spines that get stuck in human skin and cause extremely painful stings. The stings can cause many symptoms including burning, swelling, nausea, extreme pain and numbness. Very unpleasant stuff.

The even fuzzier caterpillar.  Image credit: Don Hall, from http://www.huffingtonpost.com/2014/09/10/puss-caterpillar_n_5794246.html

The even fuzzier caterpillar.
Image credit: Don Hall, from http://www.huffingtonpost.com/2014/09/10/puss-caterpillar_n_5794246.html

Unfortunately for us, the adult stage of the puss moth doesn’t last very long, which means the venomous caterpillars are around a lot longer than the friendly moths. The adults only live for about a week, and usually lay their eggs the night they emerge from their cocoon. The larvae go through a number of moults, getting hairier with each stage. When they are ready to build their cocoons, the caterpillars spin a thin framework of silk and then detach their hairy coats to complete their cosy sleeping bag. It’s a handy technique, but kind of gross in a way.

While puss moth caterpillars are not the only venomous caterpillars in the world, they are the most venomous species in the US, so be carefully around really fuzzy, cute things. They could be dangerous.

Mexican Long-nosed Bat (Leptonycteris nivalis)

I’ve wanted to write a post about bats for a long time, but there are so many species of bat I had trouble picking one. In fact, bats are the second largest mammalian order, with around 1,240 known species, comprising almost 20% of all mammal species. So you can see why it was a daunting task to pick a single species to write about. Luckily I have my trusty Encyclopedia of Mammals, so I simply perused the ‘bats’ section until I found a worthy candidate.

Mexican long-nosed bats are not only found in Mexico, but also in the US, Honduras and Guatemala. They live in woodlands or desert scrub, roosting in caves or hollow trees during the day. They migrate to follow their food source, the agave plant. Agave nectar is the main source of food for these bats, who hover in front the plant’s flowers and stick their long noses and tongues into the flower to get the rich, sweet nectar.

A close up of the long-nosed bat, showing its funny-looking nose.

A close up of the long-nosed bat, showing its funny-looking nose. Photo credit: Rubén Galicia

Unfortunately for the bats, agave plants bloom only for a few nights before the flower dies, which means the bats have to keep moving to have a constant source of food. When they can’t get agave, the bats will also feed on flower and pollen of cacti, as well as on insects. Because of their mostly liquid diet, these bats have very little need of water, which is probably why they do so well in desert areas.

Mexican long-nosed bats are quite small, reaching only 9 cm in length and 30 g in weight. Their long nose is equipped with a triangular nose leaf, which is thought to aid the bats in smelling flowering agave plants. They have a very long tongue, which has enlarged papillae at the tip to help the bat lap up nectar.

Swooping in to get some nectar.

Swooping in to get some nectar. Source:  http://pixdaus.com/mexican-long-nosed-bat-leptonycteris-nivalis-bat-flower-natu/items/view/302980/

The bats mate in May, with young being born in the middle of the summer. A female will give birth to one baby, who piggy backs on mom for a few months until it is able to fly on its own. Mexican long-nosed bats roost in huge colonies, sometimes numbering up to 13,000 bats. Imagine walking into that cave!

Long-nosed bats have faced population declines in recent years, which is a big worry for the agave plant. The bats help pollinate the plants, so fewer bats means less agave, which is terrible news for tequila drinkers. On the bright side, conservation efforts have been ongoing since 1995, so hopefully these bats will be around for a long time to come.

Cover image source: http://pixdaus.com/mexican-long-nosed-bat-leptonycteris-nivalis-bat-flower-natu/items/view/302980/

Gila Monster (Heloderma suspectum)

I think most reptiles get a bad rap. They’re scaly, often creepy looking and a fair number of them (at least snakes) are venomous. But still, I think gila monsters get the bad end of the stick, even for a reptile. After all, they have the word ‘monster’ in their name. So today I’d like to share a bit about gila monsters, to try and clear their name. Or condemn them to truly being monsters. You can decide for yourself.

Gila monsters live in the southern United States and in Mexico, in desert areas where it is hot and dry. They prefer areas with some sort of shelter; either cacti and bushes or rocks and canyons. Despite their desert habitats, gila monsters seem to show a liking for water, and even bathe in puddles after it rains. So there’s a point for the non-monstrous side – gila monsters take baths. No monster would do that!

Ugly, isn't he?

Ugly, isn’t he?

On the other hand, gila monsters get pretty big. At least, I would be uncomfortable walking in the desert only to stumble across a two foot long lizard. And an ugly one, at that. Despite its colourful markings, the gila does not look very pretty. They are scaly and heavyset, with rolls of skin that just make them look creepy. Gila monsters also have pretty big claws, adding to their fearful appearance. And on top of that, gila monsters are one of only two venomous species of lizards in the world (the other being its close cousin, the beaded lizard).

Luckily for people, gila monsters move very slowly, so unless you stick your finger in a lizard’s mouth, you probably won’t get bitten. Even if you do, you’re probably not going to die, despite the venom’s potent toxicity. See, unlike snakes, who have their venom-injecting fangs on the roof of their mouths, the gila monster has its venom glands on its lower jaw. This makes it a lot harder for the lizards to give their victim a large shot of venom, so not a lot generally enters the victim’s body. So yes, they have venom and can bite, and they don’t really let go (there are stories of having to fully submerge a gila monster in water before it would release its bite), but they are slow and easy to avoid, and don’t poison you that much.

A gila monster showing off its large claws.

A gila monster showing off its large claws.

Gila monsters have voracious (one might say monstrous) appetites. They usually eat eggs, but also feed on any small animals they can find and also sometimes consume carrion. And when gila monsters eat, they eat. Adults can consume up to 35% of their body weight in one sitting; young can eat up to 50%. This is an adaptation to the scarcity of their food – in the wild gila monsters only eat five to ten times a year. They have an incredible sense of smell, and can detect eggs buried six inches in the sand. They can even follow the trail of an egg that has rolled down a hill.

So all in all I think gila monsters are treated unfairly. They may be ugly, large and venomous, but that doesn’t make them monsters. They’re just a group of animals doing their best to get by in this crazy world. There are many wild myths about about gila monsters. One is that their foul-smelling breath is toxic and can kill animals and people. One theory suggested that gila monsters had no anus, and had to expel waste from its mouth, leading to the terrible odour it exudes. There are also rumours that this poor, slow moving lizard can spit venom, or leap at things to attack them. Very, very false. Poor gila monsters. So misunderstood.