Nov 8

Despite their thick skins, crocodilians are actually more sensitive to touch than humans, according to new research.

Black caiman portrait

Black caiman with jaws open

Crocodilians – a group comprising crocodiles, alligators and gharials – possess large numbers of dome-shaped dots around their jaws, but until now the function of these structures has been unclear.

Previous theories suggested that the bumps were used to detect electrical or magnetic fields, to secrete fluid or to detect salinity. However, new research published in the Journal of Experimental Biology has found that the unusual structures are extremely sensitive to touch. In fact, they are even more sensitive than human fingertips.

When I used a calibrated series of fibres to touch or tickle the [bumps], I found that they were responsive to forces finer than our own fingertips – a sensory system widely studied for its own sensitivity,” said Duncan Leitch, one of the authors of the study.

Close-up photo of Nile crocodile teeth

Close-up of Nile crocodile jaws, showing black bumps on the skin

Network of nerves

When the researchers analysed the bumps, they found that they were made up of many specialised cell receptors. Numerous free nerve endings occurred near the surface of the bumps, while deeper in the skin were structures sensitive to pressure and vibrations.

By tracing the nerves, the researchers also found that the Nile crocodiles and American alligators they studied had a delicate network of nerves running throughout their jaws, threading through the skull before ending in the bumps. The scientists suggest that this layout, with the nerve network largely enclosed within the skull, may help to protect the nerves during aggressive encounters or when the animal is hunting.

Photo of American alligator walking

American alligator

Sensitive armour

The super-sensitive nature of crocodilians’ jaws may play a role in their rapid reaction times when hunting, allowing them to effortlessly detect movements in the water. It may also allow these armoured reptiles to more easily distinguish between food and inedible debris.

I was very surprised at these results, especially considering how armoured and scaly the crocodiles and alligators appear,” said Leitch. “However, it seems to make sense that an animal that might need to carefully discriminate between inedible objects and food, especially in dark or nocturnal environments, would be well-served by having an exquisite sense of touch.”

Despite their large size and fearsome reputation, female crocodiles can also be incredibly gentle, using their jaws to help their eggs to hatch, and even carrying their offspring in their mouths. Having highly sensitive jaws is an obvious advantage in performing these delicate, controlled movements.

Photo of female American alligator carrying young

Female crocodilians, like this American alligator, take great care of their eggs and young

Evolutionary puzzle

According to Leitch, one of the goals of the research is to gain a better understanding of how the nervous systems of different species – in this case, crocodilians and humans – have evolved to solve similar problems, such as the processing of touch sensations.

As ancient reptiles that have been around for millions of years, crocodilians can play a key role in our understanding of evolutionary processes.

Nile crocodile eye close-up

Close-up of Nile crocodile eye

It is interesting to consider what adaptations, including possibly sensory capabilities, have made them such robust creatures,” said Leitch.

Read more on this story at BBC Nature News – Crocs have super-sensitive jaws.

View photos and videos of crocodilians on ARKive.

Liz Shaw, ARKive Text Author

Oct 11

An unusual species of turtle has been found to excrete waste substances through its mouth, according to a team of scientists in Singapore.

Photo of the head of a captive Chinese softshell turtle

The scientists were puzzled by the behaviour of the Chinese softshell turtle (Pelodiscus sinensis) as, despite needing to breathe air, it often submerged its head in water for up to 100 minutes at a time.

When they studied the turtle in the lab, the team found that it regularly dipped its head into water and rinsed it through its mouth. The rhythmic motion of its throat, not to mention the fact that it did not drown, indicated that it was still ‘breathing’ while submerged.

Photo of a Chinese softshell turtle hauled out on log, damselfly on back

Excreting urea

After testing the water, the scientists found increased levels of the chemical compound urea, a nitrogen-rich waste substance that is excreted by most vertebrates via the kidneys and passed out as urine. In turtles, urea normally passes out of the cloaca, a single orifice used for excretion and for reproduction.

However, the team’s findings showed that the Chinese softshell turtle excretes significantly more urea through its mouth than through its cloaca. This adds to previous research that indicated that this species has highly specialised mouth tissues, a fact first discussed over a century ago when it was suggested that their velvety mouth functions in a similar way to fish gills. The findings of the research have been published in The Journal of Experimental Biology.

Portrait photo of a captive chinese softshell turtle

According to Professor Ip Yuen Kwong, one of the researchers, “These results indicate for the first time that [mouth tissue] processes and rhythmic [throat] movements were involved in urea excretion in P. sinensis.”

We were greatly surprised by our novel results because it is generally accepted that the kidney is responsible for the excretion of urea in vertebrates – except fish,” he said.

Farmed for food

An odd-looking turtle with a leathery shell, the Chinese softshell turtle is native to much of East Asia, occurring in China, Japan, Taiwan and Vietnam. It has also been introduced to Thailand and the United States.

Photo of Chinese softshell turtle on ground

The Chinese softshell turtle is typically found in swampy, brackish water, and the scientists have suggested that the ability to excrete urea via the mouth may have helped this and other soft-shelled turtles to successfully invade brackish and marine environments.

To produce urine in the kidneys, the turtles would have to regularly take in water, which would be harmful when the water is too salty. By simply rinsing its mouth with the brackish water, the turtle can avoid the problems associated with drinking it.

The Chinese softshell turtle may also be able to take in oxygen through its mouth tissues.

Considered a delicacy in many parts of Asia, this species is farmed in vast numbers for food, but its wild populations also continue to be exploited. As a result, the Chinese softshell turtle is in decline, and has been classified as Vulnerable on the IUCN Red List.

Read more on this story at BBC News – Chinese turtle passes waste urea through its mouth.

View more photos and videos of turtles on ARKive.

Liz Shaw, ARKive Text Author

May 8

This week, two male cuckoos that were fitted with satellite tags in May last year have become the first of their kind to have their African migration mapped.

Female cuckoo image

The cuckoo is a well-known harbinger of spring in Britain

Avian air miles

In the last two decades, Britain has lost almost half of its cuckoo population, and numbers are continuing to decline steadily. However, conservation of the cuckoo has been hampered by a lack of information surrounding the cuckoo’s long migration to and from its breeding grounds.

In an effort to understand more about this extraordinary species, the British Trust for Ornithology (BTO) fitted five male cuckoos with small satellite tags in May last year. It was hoped that following these avian adventurers would help scientists to discover why fewer and fewer cuckoos are returning to the UK each year.

Two of the birds, named Lyster and Chris, are helping scientists to unravel the mystery of the cuckoo’s migration. After a remarkably long journey – Lyster clocked an incredible 10,000 miles in total – both birds arrived back in the UK last week. Lyster was spotted in the Norfolk Broads on Tuesday, just 10 miles from where he was tagged last May.

It’s just fantastic,” said Dr Phil Atkinson, head of international research at the BTO. “We know where he’s been, we know the routes he’s taken and now he’s back in the Broads.

Cuckoo chick image

Reed warbler feeds a cuckoo chick in its nest

Route revealed

By tracking Lyster and Chris, scientists were able to create a migration map, which revealed exactly where the cuckoos spent the winter. The map also highlighted how little time cuckoos, which are often thought of as British birds, spend in Britain.

They’re African birds, really,” said Phil Atkinson. “They evolved in Africa.

Missing on migration

Unfortunately, three of the birds didn’t make it back to Britain. As with all migratory species, cuckoos respond to the changing seasons, and rely on the presence of lush vegetation to provide food for the insects that they feed on. This means that a changing climate could create additional barriers along their already arduous journey.

All the birds got down to Congo and survived, and it’s only on spring migration that we started to lose birds,” said Dr Atkinson. “We lost our first bird, Clement, in Cameroon on the return journey. So we think the crunch time is just before they cross the Sahara.

The loss of the birds was a blow to the research team. However, the new information gleaned from this event regarding the most challenging parts of a cuckoo’s migration could actually help with the conservation of the species.

These birds move into West Africa, they fatten up as much as they can – enough to fuel their Saharan crossing. And if they’re not able to do that, I think that’s going to be a real pinch point in terms of mortality,” said Dr Atkinson. “That’s where we need to focus our research effort and conservation action.

Male cuckoo image

Male cuckoo in flight

Next steps

Following the success of the tagged males, the team now plans to continue its research by fitting female cuckoos with the same devices and tracking their progress. The team is keen to find out if migration patterns, both in terms of route and timing, are different between males and females.

Male cuckoos may need to return to the UK earlier than females in order to ensure they occupy a good territory and find females to mate with, while the females may have to stay in the UK later than the males, to lay the last clutch of the season.

As we have seen in the five cuckoos, timing is really important and this may be crucial in determining whether a bird undertakes a migration successfully or not,” said Dr Atkinson.

Grahame Madge, of the RSPB, praised the tagging study, and expressed relief that some cuckoos were successfully completing their migrations and returning to Britain to breed.

The cuckoo is an urgent priority for research,” he said. “This fantastic project is boosting the understanding of this bird so that, hopefully, we can give this bird a future.

Read more on this story at BBC – Tagged cuckoos complete migration and return to the UK.

Learn more about the cuckoo on ARKive.

Kathryn Pintus, ARKive Species Text Author

Feb 29

Today only comes around once every four years, so I hope that you are making the most of this leap day! To celebrate the leap year, we have sprung into action and hopped around the ARKive collection to find ARKive’s Top Ten Leapers!

California jumping gall wasp  (Neuroterus saltatorius)

The California jumping gall wasp may look like an unpromising contender for the top ten leaping list, however these tiny galls will jump for three days – as shown in this video. The tiny wasp larvae inside the gall flip themselves, although exactly why is not known.

California jumping gall wasp image

Lesser florican  (Sypheotides indicus)

The male lesser florican can leap up to two metres into the air in order to attract females. Helped by an energetic flurry of wing beats, this species may repeat this seductive aerial routine up to 500 times a day!

Male lesser florican display jumping during breeding season

Eastern grey kangaroo  (Macropus giganteus)

Perhaps the most famous of leapers, we couldn’t possibly have left the kangaroo off this top ten list. The eastern grey kangaroo is able to travel at great speeds, using its powerful, enlarged hindquarters for leaping, aided by the long tail, which acts as a balance and rudder.

Male eastern grey kangaroo jumping image

Verreaux’s sifaka  (Propithecus verreauxi)

Verreaux’s sifaka is aptly designed for leaping between tree trunks. When crossing open spaces, this species will descend to the ground and bound along on its hind legs with its arms held out rather like a graceful dancer!

Verreaux's sifaka 'dancing' photo

Brown hare  (Lepus europaeus)

During its famous boxing matches, the ‘mad March hare’ can leap to pretty impressive heights. Boxing bouts between hares occur between an unreceptive female and an overenthusiastic male during the mating season.

Pair of brown hares boxing in spring image

Blackbuck  (Antilope cervicapra)

It can be quite hazardous being a blackbuck, as they are preyed upon a number of species such as wolves and leopards. Luckily, this species has speed on its side and can leap extraordinarily high into the air on seeing a potential predator, before galloping away at up to 80 kilometres an hour.

Female blackbuck leaping image

Common tree frog  (Hyla arborea)

The common tree frog has mastered the ability to eat fast food. It can make long leaps in order to catch fast flying insects, as demonstrated in this multiflash sequence image.

Common tree frog, multiflash jumping sequence

Common field grasshopper  (Chorthippus brunneus)

Ever tried to catch a grasshopper? It’s quite difficult! Grasshoppers, like this common field grasshopper, have a special muscle system in the hind legs which store energy like a catapult. When the grasshopper is disturbed it releases the energy allowing the grasshopper to jump long distances!

Female common field grasshopper image

Himalayan jumping spider  (Euophrys omnisuperstes)

As its name suggests, the Himalayan jumping spider lives high in the Himalayas, and with legs working like pistons it is able to jump up to 30 times its own body length.

Himalayan jumping spider, front view

Smoothtail devil ray  (Mobula thurstoni)

Exceptionally graceful swimmers, rays appear to fly through the water on their large wings. Rays, like the smoothtail devil ray, are also able to leap entirely out of the water, possibly in a form of communication or play.

Smoothtail devil ray leaping out of the water image


Lauren Pascoe, ARKive Media Researcher

Jan 1

It’s that time of year again, the turkey supply has been exhausted, the sales have been ransacked and the festive celebrations are nearly over! But fear not, we are here to inspire some New Year cheer and get you in the mood to tackle 2012 head on, starting with planning those New Year’s resolutions!

Photo of American black bear scratching head

In need of some help with your New Year's resolutions?


Work on that waistline

After all the overindulgence of the festive period, one of the most popular resolutions has got to be to lose a little weight. This can be hard to master on cold winter nights, so we suggest you look to the dedicated emperor penguin for a little guidance. Emperor penguins are the only bird species to brave the bitter Antarctic winter, with males enduring the constant darkness of the winter months in order to incubate their egg.

Photo of emperor penguin adult and chick walking along ice

Emperor penguin males lose up to 50% of their body weight while incubating their egg

This often results in the males losing as much as half of their body weight – more through necessity than choice, but still a stunning example of how hard work and endurance pay off!

Get fighting fit

If dieting is not your thing, why not knock lethargy on its head this New Year and get fit. Take a leaf out of the spinner dolphin’s book, this acrobatic mammal can be seen leaping from the water and spinning through the air in tropical seas worldwide. If spinning isn’t your idea of a good time, why not try your hand at some of the other activities enjoyed by our animal assembly including sprinting, long distance running, diving or boxing?

Photo of spinner dolphin leaping and spinning

Spinner dolphins are certainly not lacking in energy!


Break down your language barrier

¿Por qué no aprender un nuevo idioma? Or for those not familiar with Spanish – why not learn a new language? This is a resolution that I think would be endorsed by the Albert’s lyrebird, who has a spectacular array of sounds in its arsenal, developed due to the awesome ability to accurately mimic other species.

Photo of Albert's lyrebird male displaying and calling

Why not learn a new language?


Looking for love?

If the festive spirit has left you feeling romantic then why not look for love in 2012, but do spare a thought for the animals that put their life on the line to do the same. Male ladybird spiders have to tread carefully when approaching the burrow of a prospective female in order to correctly pluck the trip wires surrounding the burrow entrance. One wrong move and the female may mistake him for her next meal!

Photo of male and female ladybird spiders with egg sac

The male ladybird spider (right) has to be careful not to end up as dinner!


Give a helping hand

As social beings we tend to gain satisfaction from helping others, whether by volunteering our time or donating our resources. In biological terms this is known as a mutualistic relationship and there are plenty of examples of this in nature. The fanged pitcher plant has a mutualistic relationship with a particular species of ant which forms nests in the hollow tendrils of the plant. The ant is able to traverse the inner walls of the pitcher plant without falling in and being digested by the plant and is even able to safely hunt in the pitcher fluid.

Close up photo of a pitcher of the fanged pitcher plant

The fanged pitcher plant happily houses ants in return for a favour

In return the ant removes large prey items from the pitcher fluid. If left they would begin to decay before they were digested, which could be detrimental to the pitcher plant – win win I’d say!

Out with the old and in with the new!

What better time of year to embark on a spring clean; delve through those drawers and finally get to the back of that wardrobe. Everyone feels better after a good tidy up and it seems that this is not restricted to just us humans, the Vogelkop bowerbird also likes to maintain a tidy living space. The males pay meticulous attention to the position of each of the decorations within their conical bower, as after all, no self-respecting female bowerbird is going to choose a male with an unkempt bower.

Photo of male Vogelkop bowerbird in bower arranging ornaments

The male Vogelkop bowerbird likes to keep his bower neat and tidy


Got itchy feet?

The world is a fascinating place with scores of spectacular sights to see, meaning travel is an increasingly popular aspiration. There are many epic journeys occurring in the animal kingdom annually, and it’s not only birds and mammals that migrate. The monarch butterfly makes one of the largest invertebrate migrations, covering distances as great as 3,000 miles to their wintering grounds.

Photo of large numbers of monarch butterflies in flight

Monarch butterflies undertake massive annual migrations - where will you go?

This doesn’t mean you have to travel hundreds of miles to discover something new of course. Why not uncover some hidden treasures closer to home, see what can be found near you using Search by Geography.


Good luck with any resolutions made, from all here at ARKive we wish you a very Happy New Year!

Laura Sutherland, ARKive Education Officer


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