Saltwater Crocodile (Crocodylus porosus)

During the past two weeks I watched all four Jurassic Park movies, so I’m in a bit of a dinosaur mood. Unfortunately, Our Wild World is a blog about extant animals, so dinosaurs are right out. I’ve decided instead to write about a species of crocodile, because they’re basically the next best thing.

The species I’m going to focus on is the saltwater crocodile, because they are super cool. Saltwater crocodiles have a broad range, and are found from eastern India to Indonesia, Australia, and even around some Pacific islands, like Vanuatu and the Solomon Islands. As their name implies, saltwater crocs can tolerate high levels of salinity, and are often found in rivers, estuaries and coastal areas. More than any other species of crocodile, saltwater crocodiles are found in the ocean; they often travel long distances in the open ocean and can spend months at sea.

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The range of the saltwater crocodile. Image source: Wikipedia 

Saltwater crocodiles are big. You definitely don’t want to meet one of them in a murky river. In fact, saltwater crocodiles are the biggest of all crocodiles and are the biggest reptiles in the world. Males can reach lengths of six to seven meters, though females only grow to a paltry three meters. The largest male ever recorded weighed 1,075 kg. Adults are a dark greenish colour, with lighter bellies. Young crocodiles have more exciting colouring, being yellow with stripes and spots on them.

Crocodiles are big (as I mentioned), and they have large, pointy teeth. Saltwater crocodiles have between 64 and 68 teeth, the longest of which can measure up to nine centimetres in length. They use these massive teeth to hunt, feeding on a wide variety of animals such as fish, turtles, snakes, buffalo, birds, wild boars and monkeys. Crocodiles are ambush predators, hiding below the water’s surface with only their backs, nostrils and eyes visible, until an unlucky victim stumbles along.

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A very fat looking saltwater crocodile. Image credit: fvanrenterghem via Wikipedia

When a prey animal does happen to wander too close to a saltwater crocodile, the crocodile strikes. They are surprisingly fast when striking from the water, using both feet and their tails to launch themselves at their prey. They can swim in bursts of 24 to 29 km/hr, so you really don’t want to be stuck in the water with a saltwater crocodile.

Once the crocodiles have an animal in their strong jaws, it is either swallowed whole, or, if it is too large, the crocs drag their prey underwater and drown it. Crocodile teeth are not made for shearing, so crocodiles rip chunks of meat off their prey by rolling in the water while gripping the prey to twist off pieces of flesh, or by jerking their heads to remove hunks of tasty meat.

If you do end up getting bitten by a saltwater crocodile, good luck getting away; saltwater crocodiles have the highest bite force of any animal, measuring a maximum of 16,414 N (which I’m guessing is a lot). Part of the bite strength of saltwater crocodiles comes from the design of their jaw muscles; they can clamp down extremely hard, but have weak muscles when it comes to opening their jaws. Apparently a few layers of duct tape is sufficient to hold a crocodile’s mouth shut. The tricky part, of course, is getting the duct tape on the crocodile in the first place.

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Saltwater crocs can breach out of the water to try and catch food, so don’t think you’re safe just because you’re in a tree. Image credit: Matt via Wikipedia

Saltwater crocodiles breed during the wet season, from September to October. Though they often live in saltwater, saltwater crocodiles move to fresh water to breed. Males are very territorial in general, but are especially aggressive during the breeding season, chasing away any other males that encroach on their territory.

Female saltwater crocodiles lay between 40 and 90 eggs in mounds placed on river banks and shores. The eggs are laid raised from the ground, to prevent them from being washed away during floods. The eggs hatch after around three months, at which point calls from the young prompt the mother to help unearth the eggs. She then carries the hatchlings in her mouth to the water, and stays with her brood for a few months. Very few survive to adulthood, and those that do disperse at eight months of age. Sexual maturity is reached when crocodiles are 10 to 16 years old, and these remarkable reptiles can live to be over 70 years of age.

Because saltwater crocodiles are highly valued for their meat, eggs, and skin, this species was once hunted extensively. They have since come under protection in most of their range, and have made great recoveries. Thankfully they are not currently endangered or threatened, but habitat destruction is a concern for these magnificent beasts.

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My drawing for the week (I apologize for the poor quality of the image – I’m away and do not have access to my scanner) – this is all you would see of a crocodile hiding in the water. 

I’d like to say a few last things about the saltwater crocodile. First, they are big, with large teeth, and are territorial and aggressive. So yes, they can and do eat people who come into their waters, so watch out. And secondly, even though these guys are giant man-eaters, you shouldn’t hate them, because not only are they very cool, they are also supposed to be very intelligent. They have extensive means of communication, can learn tasks quite quickly, and track the migratory patterns of their prey. So don’t hate saltwater crocodiles, and definitely don’t swim with them.

Cover image credit: Djambalawa via Wikipedia

Tarsier (family Tarsiidae)

In general, the bigger an animal’s eyes are, the cuter they are. Just think of kittens, who have huge eyes and are freaking adorable. But there are certainly exceptions to this rule, and tarsiers are one of them. Their eyes are so big that these guys just look creepy.

Tarsiers are primates, and make up the family Tarsiidae. The exact number of tarsier species is up for debate, as well as what genera they are placed in. All extant species can be found in southeast Asia, in places such as Sumatra, Borneo, Sulawesi and the Philippines, though tarsier fossil records have been found in North America, Europe, Africa and Asia.

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A Philippine tarsier. Image credit: Jasper Greek Golangco via Wikipedia 

Tarsiers are built for living in trees, and all species are arboreal. They like very dense, tropical forests, though different species can be found at different altitudes. Tarsiers roost in hollow trees or clusters of vines, so availability of roost sites is important for tarsier habitats.

Tarsiers are very small primates, with their bodies only being ten to fifteen centimetres long. Tarsiers have soft, floofy fur, which is dark brown or greyish, to blend in with dead leaves or bark. They have very long hind legs, which can be twice as long as the body. These are specialized for clinging and leaping among the trees.

The length of tarsiers’ hind legs is due to the elongation of the tarsal bones in their feet, hence the name ‘tarsier’. In most animals with long hind legs, this lengthening is due to an elongation of the metatarsals, not the tarsals. Tarsiers are unique in this respect, and the elongation of the tarsals means that they can have long limbs without losing any dexterity in their toes.

Of course, the most notable feature of tarsiers is their absolutely ridiculously huge eyes. They are each about 16 mm in diameter, and each weighs almost as much as a tarsiers brain. These giant eyes help tarsiers track their prey at night, though they also have extremely acute hearing which helps them detect any tasty meals that flutter by.

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Look how freaking creepy their eyes are! Image credit: mtoz via Wikipeida

You see, tarsiers have a very odd diet — in fact, they are the only truly carnivorous primates. They feed mainly on insects, including moths, butterflies, ants and beetles. Tarsiers will also feed on larger prey, such as birds, snakes and lizards.

Tarsiers give birth to one offspring, after a gestation of around six months. The young are large, weighing 25 to 30% of their mothers’ body weights – the largest birth weight relative to maternal mass of any mammal. They can climb the day they are born, and reach sexual maturity within two years. Though some tarsier species are solitary, others live and roost in family groups.

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Okay, baby tarsiers are kind of cute. Image source

Tarsiers rely very heavily on the habitats that house them; as such they are very vulnerable to habitat destruction. The key to protecting this very unique family of animals is to protect the forests they live in. Hopefully we can preserve the forests and preserve these super cool (if very ugly) primates!

Hairless Bat (Cheiromeles torquatus)

Bats are cute, furry creatures that I’ve always liked and admired. Still, in a large order of animals like the bats, there are always going to be a few that are weird and… less cute. Maybe even ugly. Today’s animal, at least to me, falls in that category. But you can judge for yourself.

Hairless bats live in Southeast Asia and Oceania; in Malaysia, Sumatra, Java, Borneo, the Philippines and Thailand. They roost mainly in caves or hollow trees. They are found in lowland areas, and roost in large colonies. In some parts of its range, the hairless bat is quite uncommon, while in others it is considered a pest.

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A hairless bat showing off its hairless body. Image source

Hairless bats have a body length of 13 – 14.5 cm, with an additional 5.6 – 7.1 cm coming from the tail. They have black skin that is thick and is all wrinkly and weird looking. These bats have pouches along both sides of their bodies, which open towards the back ends of the bats. They can tuck their wings into these pouches, which then allows the bats to crawl around on four feet without impediment.

The most obvious feature of hairless bats is their lack of fur. They aren’t completely hairless, though, as they have hair in some odd spots on their body. A patch of hair covers the bats’ throat pouches, from which a strongly scented secretion is exuded. Another strange spot for hair is the bats’ first toes on each hind foot — these are covered in bristle-like hairs, and have flat nails instead of claws. These toes are believed to be used for grooming.

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A close up of a bat’s bulldog-like head. Image source

Hairless bats are insectivorous, and usually hunt in the early evening. Because of their relatively large size, hairless bats have less to fear from predators, and so can leave their roosts earlier than other bats, getting the best choice of food. They generally hunt over streams or clearings, eating termites and other insects.

Hairless bats are also known as naked bulldog bats, because their heads look a bit like bulldogs. As I said, I don’t really find them that cute (I’m not a huge fan of bulldogs). Still, some people might find these guys adorable, you never know.

Giant Freshwater Stingray (Himantura polylepis)

I’ve always thought of stingrays as saltwater animals, though I don’t have any particular reason to think this. But there are freshwater rays, and today’s animal also has the distinction of being the largest of the freshwater stingrays. It is unimaginatively called the giant freshwater stingray.

These animals are found rivers in southeast Asia; in Thailand, Malaysia, and Borneo. Giant freshwater rays tend to hang out at the bottom of rivers, and especially like muddy and sandy areas. They are sometimes found in estuaries, but there have been no reports of these stingrays in fully marine habitats.

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A map of the distribution of the giant freshwater stingray. Image source: Wikipedia

As I mentioned, these stingrays get pretty big. Did I say pretty big? I meant huge. Giant, even. They can reach widths of almost two meters and lengths of five meters (though much of this is thanks to the rays’ long tails), and weigh in at 500-600 kg. The stingrays’ tails are equipped with a spine near the base. This spine measures over 35 cm long, making it the largest spine found on any stingray. Giant freshwater rays are coloured perfectly for a life on muddy river bottoms, being brown on top and light on the bottom.

Giant freshwater stingrays mainly rely on electric signals to sense and catch their prey, which mainly consist of small, bottom-dwelling fish and invertebrates, such as crustaceans and molluscs. The stingrays themselves have very few predators, thanks to their massive size. Even small stingrays are hard to hunt, thanks to their colouring and that stinger on their tails, which is covered in a toxic mucus.

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A giant freshwater stingray in captivity. They tend to do quite poorly in aquaria, because it is difficult to provide them with adequate food and space. Image source

Not a lot is known about reproduction in giant freshwater stingrays. It is believed that the rays find mates using the same electrical sensory organs that help them hunt. Once females have mated, they head into estuaries, which act as nursing grounds for the rays. They give birth to one to four live young, and care for them until they are ready to move into freshwater areas.

As is the case with most giant, interesting species, the freshwater stingray has suffered from population declines in recent years. They have been hunted for meat, aquaria and sport, and also are affected by habitat degradation. The giant freshwater ray is currently considered endangered, and thus far conservation programs have proved ineffective.

I have a mild fear of swimming in oceans, because I have an active imagination and can picture all the giant creatures swimming beneath me. I’ve always felt quite a bit safer in rivers and lakes, but after writing about some terrifyingly large freshwater critters, I’m not so sure. Maybe I should just avoid swimming altogether. Can you imagine one of these guys swimming up beside you as you take a leisurely dip in the Mekong? I think I would faint.

Social Wasp (Parischnogaster jacobsoni)

Most species of animals are classified by scientific names, and are known to the public by one or more common names. Unfortunately today’s animal doesn’t have a common name. I’ve called it a social wasp because that’s the group the species belongs to, and will refer to it as ‘wasp’ for the remainder of this post.

These wasps are found in rainforests in southeast Asia, and are particularly common in Malaysia. They build nests in humid areas, such as near water or in caves. Despite their preference for living in nests, these wasps tend to build their nests in open spaces, and sometimes near humans. Because of this tendency, this species is one of the more well-known of its genus.

What a colony of these wasps looks like. Not super impressive.  Photo credit: Turillazzi Stefano via Wikipedia

What a colony of these wasps looks like. Not super impressive.
Photo credit: Turillazzi Stefano via Wikipedia

This species of wasp is long and thin, with males having white stripes on their bodies and females being black or dark brown. Nests usually house up to six males and six females, along with over 30 larvae. The nests are quite primitive for wasps, and are constructed from plant materials.

Social behaviour in these wasps follows a reasonably complex system for wasps. The female with the most reproductively developed ovaries is the most dominant. She bullies and intimidates the females with the next most developed ovaries, and generally ignores those with undeveloped ovaries. This is thought to occur because dominant females may be able to repress reproductive development in subordinate ones, and the alpha female isn’t too concerned about being usurped by females with tiny little ovaries.

A close up of some waspies.  Photo credit: David Baracchi via Wikipedia

A close up of some waspies.
Photo credit: David Baracchi via Wikipedia

Members of wasp colonies are very aggressive, especially to those who are not members of their nests. They can recognize their nest-mates, and will attack any other wasps. Experiments have shown that these wasps can recognize their friends even when those friends are corpses, which implies the recognition is not due to active signalling on the wasps’ parts.

This species has an enlarged gland on its abdomen that secretes special substances, the main purpose of which is to protect the wasps’ nests. The wasps will rub their secretions along the stems that run to their nests, which catch any pesky invaders, such as ants. Other functions of the secretions include self-grooming, which can protect against diseases, and rearing broods.

Insects often have complex lifestyles, and although these wasps certainly don’t have as rich a social life as many bees and ants do, I still think they are pretty cool. Especially that part about guarding their nests against ants. That’s thinking ahead.

Cover Image credit: David Baracchi via Wikipedia.

Tapir (family Tapiridae)

Tapirs are strange animals. I first heard of them when I was younger and playing Zoo Tycoon. The funny thing is, I had the ultimate edition of Zoo Tycoon which included extinct and some imaginary creatures. So for a long time I wasn’t sure whether tapirs actually existed or not.

It turns out tapirs are actual animals, and that there’s five species of them. Four species live in Central and South America, while the fifth is found in Southeast Asia. Tapirs live in forested areas, both in lowlands and mountains. Though they are land animals, all tapirs love water, and will happily splash around in flooded forests or mountain streams.

Tapirs look a bit like a hippopotamus crossed with an elephant, with maybe some horse thrown in for good measure. They are generally around 2 m long and 1 m high at the shoulder, weighing between 150 and 300 kg. They have short, bristly fur on their bodies, which is dark brown in all species except for the Malayan tapir, which has a large white patch on its midsection. The most prominent feature of tapirs are their funny-looking noses, which are formed from the snout and upper lips.

The noses of tapirs are used to grab food from trees and other foliage. The noses are quite moveable, able to reach in any direction. Tapirs are herbivores, eating the leaves, buds and fruits of any low-hanging plants. They also often consume aquatic plants, walking on the bottom of rivers and streams to find nice tasty plant morsels. To deal with the large amount of vegetation in their diet, tapirs are hindgut fermentors, meaning bacteria in the cecum of the digestive tract help digest the tough plant fibres in the animals’ diets.

Baby tapirs are pretty cute. All species of tapir give birth to striped babies, having one calf about every two years.  Image credit: Patrick Bolger Photography

Baby tapirs are pretty cute. All species of tapir give birth to striped babies, having one calf about every two years.
Image credit: Patrick Bolger Photography

Aside from the breeding season, tapirs are solitary animals. They are usually nocturnal, and spend most of their hours wandering around and looking for food. As I mentioned before, they are water lovers, and will often lounge in water to cool off. As well, if tapirs feel threatened, they usually just head to the nearest water hole and submerge themselves until the predator leaves. When cornered, though, they can be pretty dangerous because they have very strong jaws.

Unfortunately for tapirs, hunting and habitat loss has reduced numbers worldwide. Currently all species of tapir are considered endangered or vulnerable. Luckily I think these guys are so strange looking that conservation efforts will continue to try and keep tapirs around for a long time.

Cover image source: http://www.zoobarcelona.cat/en/know-the-zoo/animal-files/mammals/detail/tapir-amazonic/