Friday, 26 September 2014

Top 5 Strangest Caterpillars

Before I start rambling on about strange-looking caterpillars, I'd like to tell you about a few things that I've been doing lately. On Kinder (you might remember this brownfield site, I've mentioned it a few times before) we looked under a big bit of wood and found 9 Common Toads (Bufo bufo)! There were some large adults, and a few juveniles too. There were also 2 voles, and they'd made a nice little nest out of dried up grass.
Also, we've noticed a nice laurel bush near where I live. The flowers are attracting lots of butterflies, and we've found lots of Red Admirals (Vanessa atalanta) there. Barry, an entomologist friend of ours, says that we should keep an eye on the bush as it may attract rarities!

Anyway, I'll get on with the strange caterpillars now.

Puss Moth caterpillar (Cerura vinula)

The adult moth of this caterpillar has soft fur that feels like that of a cat's - giving it the name Puss Moth. The caterpillar feeds on the leaves of trees such as Poplar, Sallow, and Willow.
The strange-looking caterpillar, with its 2 'tails' and its red-ringed face, is certainly a sight to behold. If it is disturbed, then it rears up like a snake and shows its bizarre head. This, along with a little tail waving, usually scares off any potential predators. If it doesn't work though, the caterpillar has another trick - it squirts formic acid from its head.
Before the caterpillar pupates, it changes colour to orange then purple, then it will spin a silk cocoon and stick pieces of bark to it for camouflage.

Harris Three Spot Moth (Harrisimemna trisignata)

The adult, with its attractive markings, is quite a nice moth. In comparison, its caterpillar looks pretty ugly and dull. However, this wide-spread little caterpillar has an amazing survival strategy. Not only does it mimic bird droppings to avoid predators, but it uses heads as clubs! Sounds more like an ogre's weapon, not that of a little caterpillar. This larva retains its shed heads from previous moults, and attaches them to long, stiff hairs. If its bird dropping disguise fails, then it will force the predator to retreat by clubbing it with its heads. If that isn't strange, then I don't know what is.

Southern Flannel Moth caterpillar (Megalopyge opercularis)
Just when you thought that things couldn't get any more bizarre, you saw that fluffy thing. Believe it or not, it's a moth caterpillar! Because of its slight resemblance to a Persian cat, it is sometimes called the Puss Moth caterpillar. Because of the other species that goes by the same name, I'll stick with the caterpillar's other name - Southern Flannel.
The long, fur-like setae looks like it would be very nice to touch and stroke. If you live in an area where Flannels can be found (United States, Mexico, and Central America) then DON'T touch it! The caterpillar has venomous spines concealed amongst its 'fur', and if these spines puncture your skin, the effects can be very severe. Nausea, rashes, numbness, head ache, swelling, and even difficulty in breathing have all been reported. 

Lobster Moth caterpillar (Stauropus fagi)

Named because of the larva's  slight resemblance to a lobster (personally, I can't really see the similarity), this is probably the weirdest caterpillar in the UK.
When the caterpillar hatches from an egg, it looks strangely like a stretched out ant! It also wriggles if disturbed, in a manner similar to an injured ant. Ants can bite and sting, so perhaps this is why the caterpillar mimics an ant - to trick predators into thinking that it could inflict pain.
As the caterpillar grows and moults, it grows stranger. It's front limbs lengthen and its anal segment becomes enlarged. When it hangs motionless from a branch, it looks rather like a dead leaf. If this camouflage fails, then it will raise its long legs in a threatening posture.
This amazing caterpillar can grow up to 7cm long!

Glass Jewel Moth caterpillar (Acraga coa)

This is my number 1 strangest caterpillar. Both the larva and the adult are pretty strange - the caterpillar is translucent and looks like it's made of blown glass, and the moth looks like it's got furry boots on.
The caterpillar was discovered on a mangrove tree leaf in Mexico, 2012. The reason for the larva's translucent body is unknown. Like its relatives, it is quite slimy. Members of its family are sometimes called 'slug caterpillars'! The sliminess is thought to deter predators and make them distasteful and difficult to get a hold on.
Other than that, we really don't know much about the Glass Jewel caterpillar. More research will be needed before we will be able to fully understand this amazing creature.

Until next time, keep on the wild side!

Wednesday, 24 September 2014

Species of the Week: Caecilians

Most people, if shown the image above, would call the creature a worm. They would be wrong. Nor is it a snake, or even a strange sort of eel. It's actually a strange amphibian called a Caecilian. These weird creatures aren't very well known amongst the general public, and spend most of their time burrowing underground. They can be found in several tropical regions of the globe.
Their name comes from from the Latin 'caecus', meaning 'blind'. This is actually wrong, they aren't blind, but their vision is limited to dark-light perception.
They have lots of folds of skin on their body called annuli, giving a segmented appearance - rather like a worm. All species of Caecilians have tiny tentacles on their head, midway between their nostrils and eyes. It is thought that these tentacles are secondary oflactory (smell) organs.

 A close up a Caecilian head, showing the small tentacles.

Little is known about the diet of these bizarre creatures. In captivity they can easily be fed completely on earthworms, and it is thought that these make up the main food in the wild. They probably will also eat other small invertebrates. To crunch on these insect snacks, they have surprisingly prominent teeth. I think that their heads look almost shark-like when you see their large teeth.

 In this image you can see the Caecilian's teeth.

Caecilians aren't just strange on the outside. If you were to cut open one of these amphibians, you would see that one of their lungs is tiny in comparison to the other. This is an adaption to having a serpentine shape, and it is a feature shared with snakes. There is even 2 Caecilian species that completely lack lungs, and absorb oxygen through their skin!
Though most are burrowers, there are also some that spend most of their time in water, like eels.
Most species give birth to live young, but a few species lay eggs in underground burrows. The female will wrap around the clump of eggs and guard them.

 A Caecilian female guards her eggs.

In some egg-laying species, the juveniles are fully developed as soon as they emerge from the egg. Others go through a semi-aquatic larval stage that spends most of the time around water.
One species goes to great lengths to ensure the survival of their young. The female will stay with her juveniles in a burrow, and she feeds them on her outer layer of skin! The babies have large teeth so that they can peel the skin away. When the outer layer of skin is gone, the babies will have to wait 3 days (the time it takes for skin to grow back) until they can have another nutritious snack. And you thought looking after your kids was hard! Imagine having to feed your children your own skin!

A female Caecilian with her babies.

 Caecilians first evolved in the time of the dinosaurs! The very first caecilian known is Eocaecilia, which lived in the Jurassic period, around 200 million years ago. It had small legs and well-developed eyes. 

 A reconstruction of Eocaecilia.

All is not well in the world of caecilians though. Amphibians can be infected with a particular type of fungus, and this fungus can cause diseases deadly to amphibians. Frogs, toads, newts, and salamanders are all threatened. Until recently, it was thought that caecilians were impervious to this fungus. However, a new study shows that caecilians can be infected. It seems that the lives of caecilians and their wonderful amphibian relatives are hanging in the balance.Scientists are researching the fungus more, in the hope that with more knowledge we may be able to save these incredible creatures. There is still hope for the amphibians.

I hope that you've enjoyed this post - I know that I have certainly enjoyed writing it. Caecilians are truly amazing creatures.

Until next time, keep on the wild side!

Monday, 15 September 2014

Species of the Week: Cuttlefish

These charismatic cephalopods have got to be my favourite marine invertebrate. I like bizarre creatures, and the cuttlefish is most certainly bizarre with its colour-changing abilities and W-shaped pupils.
Though most species are small, one amazing species can grow to 50cm long! Quite a whopper. What's more, they have one of the largest brain-to-body size ratios of any invertebrate.

An Australian Giant Cuttlefish, Sepia apama, the largest cuttlefish on Earth!

They have 10 tentacles, 2 of which are long and have a pad of powerful suckers. These are the feeding tentacles, and are used to grab prey such as crabs or fish. Once a prey item has been captured, it is paralyzed using venom in its hard beak, then eaten.
Cuttlefish can move very fast when they want to. They have flaps of skin on the sides of their body, and by undulating these flaps, the individual will be propelled forward. They also have a tube called a siphon near their head, which jets out water, allowing for quick bursts of speed.
The 'cuttle' part of the creature's name comes from the Old English name for the cuttlefish: 'cudele', which may derive from the Old Norse word 'koddi', meaning cushion, and the Middle Low German 'kudel', meaning pouch.
A porous, hard cuttlebone - the remains of an ancestral shell - is found in the center of its body. By changing the gas-to-liquid ratio inside the cuttlebone, it can regulate its buoyancy.

 A cuttlebone.

Cuttlefish blood is not red like ours. Instead, it is a curious blue-green color. This is because these creatures have the protein hemocyanin, which is full of copper, instead of red, iron-containing hemoglobin. This strangely colored blood is pumped around the body by not 1, but 3 hearts! 2 hearts pump blood to a pair of gills, and the other heart pumps blood to the remaining parts of the body.
Perhaps the most interesting thing about cuttlefish is their ability to change colour at will to match its surroundings. In fact, these cephalopods are better at colour changing than the more famous chameleons. But how on Earth do Cuttlefish achieve this? They have red, brown, black, yellow, and red pigmented chromatophores, all of them in different layers of the skin. Each pigment is surrounded by an elastic sac, which can be controlled using muscles. By opening or closing the sac around certain pigments, the cuttlefish can show different levels of the different colours.
But the Cuttlefish does not stop there with its amazing mimicry. It does not just mimic the colour of its environment, but the texture! It does this by using bands of circular muscles to force pockets of water up against the skin, forming little lumps and nodes. 

 This tiny Cuttlefish is perfectly camouflaged against these pebbles and shells.

This stunning Flamboyant Cuttlefish (Metasepia pfefferi) exhibits its ability to change its skin texture. In this picture you can see that it has used this ability to form large flaps of skin on its body.

During the breeding season, all the males in the area will crowd together and threaten each other using either bright colors or by swimming at each other, or both. Eventually all but one dominant male will back down, and the remaining individual is free to mate with all females in the area. He does so by using a specialized tentacle to insert a sperm sack into an opening close to the female's beak. A few hours later, she will begin to lay her eggs. The male will guard her valiantly while she does so. If any large males try to interrupt, the guarding male will threaten them with the methods mentioned above. If this fails, he will attempt to bite the rivals and inject paralyzing venom into them. Not all intruding males attempt the head-on approach, though. Some camouflage themselves as a harmless female so that they can sneak past the guarding male and quickly mate with the female. The round eggs are inserted onto rocks, coral, seaweed, or sea grass. The female will die shortly after mating and laying eggs. She will mate only once in her short life.

A pair of Cuttlefish mate.

  Some washed ashore Cuttlefish eggs, looking rather like grapes.

Over time, the eggs will become transparent, and the baby Cuttlefish can be seen inside. Sometimes the egg is so large for an individual that it can swim around inside it. Even at this stage they have fully developed W-shaped pupils. There is even evidence to suggest that as an adult, the Cuttlefish will prefer to prey upon creatures that it saw as a baby from its transparent egg! When the babies hatch, they will feed upon small shrimps.

A newly hatched juvenile besides an unhatched egg.

A Cuttlefish's strange pupil, looking rather like a black mustache!

I hope that you have enjoyed this week's post. Cuttlefish really are amazing little creatures!

Until next time, keep on the wild side!

Monday, 8 September 2014

Species of the Week: Pistol Shrimps

These are one of my favourite marine creatures. Most species grow no more than 5cm long, yet they compete with Sperm Whales for the award of the loudest creature in the ocean. Very impressive!
They 0ften dig burrows, and many species live on coral reefs. The majority of species inhabit tropical and temperate seas, but a few can be found in colder waters.
The most noticeable feature of a Pistol Shrimp are its mismatched claws. One is very large, the other is comparatively small. The large claw is used for hunting. When a small fish comes by, the shrimp clicks its specialized claw with amazing force. This creates a bubble that generates acoustic (sound) pressure, and as the claw extends forward, the bubble reaches high speeds. The pressure becomes strong enough to kill the fish. That isn't the full story, though. The bubble then implodes and due to high temperatures inside it, produces a short burst of light. This is called sonoluminescence. The light is of low intensity and invisible to the naked eye. However, the temperature when the bubble implodes reaches 4,700 Celsius! It has been suggested that this may help kill the prey, but it is probably just a side effect and of no biological importance. And if the shrimp is attacked by a predator, and loses its large claw, no problem! Its small claw develops into a larger one, and the lost large claw regrows as a small one.

A Pistol Shrimp displays its fascinating mismatched claws
Quite a few species of these shrimps dig extensive burrow systems. The shrimps will spend a large amount of time caring for and extending their burrow.
Many species of Pistol Shrimps have a symbiotic relationship with gobies. Instead of killing and eating it, like it would with most small fish, the Pistol Shrimp welcomes it into its burrow. They will live there together, each having a different job. While the shrimp looks after its burrow, the fish keeps a watch out for predators. They have better eyesight than shrimps, and thus make a better lookout. If a predator does approach, the goby will warn the shrimp with a flick of its tail. This relationship benefits both individuals. The shrimp gets to have a lookout, and the goby gets to have a nice, clean burrow to hide in.
This image shows the symbiotic relationship, in this case between a Yasha Goby (Stonogobiops yasha) and a Candy Stripe Pistol Shrimp (Alpheus randalli)
Probably my favourite species of Pistol Shrimp is Synalpheus regalis. It is a small species, usually no more than just over 3cm in length. They do not have a symbiotic relationship with a goby. Something like a marine equivalent of ants, they live in large colonies in sponges, inhabiting burrows running through the sponge. Every individual in the colony are the offspring of the queen, a large female individual that rules the colony. She gives birth to tiny wriggling larvae, which develop into adults. It has also been suggested that there may be a ruling male that breeds with the queen. When the sponge comes under attack by predators, such as certain species of starfish, the shrimps will defend their home by snapping at the predator to ward it off. The sound of a colony of Pistol Shrimps snapping is so loud that it can interfere with sonar equipment.
The shrimps will scrape off the outer tissue of the sponge to feed on, which the sponge tolerates in return for protection from predators.
A pair of Synalpheus regalis on a sponge
 A close-up of Synalpheus regalis

I hope that you've enjoyed this post. Look out for more Species of the Week!

Until next time, keep on the wild side!