Saturday, January 27, 2007

Chilopoda are top predators

In the world of invertebrates, top predators are not only tough, but also well equipped.

Chilopoda is a class of animals commonly called Centipedes. In Australia these are divided into five orders, of which Scolopendramorpha (to be illustrated here) contain the largest species, both in Australia and throughout the world.

The largest centipede Scolopendra gigantca, is from the tropical regions of Central America and can exceed 12 inches, 300 mm in length, whilst our largest species is little more than half that size, but it is still a large invertebrate and a top predator.

Below is an Esperance species from the same family as the largest centipede Scolopendridae, but from the genus Cormocephalus, which is very similar except for the overlapping plate behind the head. The Esperance species is one of seventeen Cormocephalus species, Australia wide.


These larger centipedes are highly solitary and will often cannibalise others during the mating process, which has probably happened in the photo above. They generally prey upon spiders, insects, slugs and worms. The larger ones will also tackle small vertebrates like snakes, lizards, frogs and small rodents. A major part of their weaponry is a pair of legs just below the head; these have evolved to form a large pair of sharp pincers that will grasp an animal and inject paralysing venom from poison glands. The other legs have sharp claws that can also hold the victim (as shown in the above photo). So with 21 pairs of legs, these guys could be described as super huggers, but as far as people are concerned, their bite although painful is not fatal (unless there is an allergic reaction to the venom).

Although centipedes are regarded as ground dwelling animals, they do climb some trees in search of prey like the centipede below, who is checking out a Banksia flower. Note the sharp claw on the ends of the legs. Those two long ones at the rear are used in display with other centipedes or for grasping prey. So as far as weaponry is concerned, these animals are very well equipped.


Although centipedes occur in desert regions, they are more common in warm tropical areas where they obtain their greatest diversity and size. Their breathing system is less efficient in dry conditions and so they mainly hunt at night and rest up during the day in rotting logs, under rocks, in burrows, under leaf-litter or tree bark where more humid conditions exist.

Centipedes have a very long history, having originated in the sea, they are related to lobsters, crabs, shrimps, etc, but they began taking to the land and semi-aquatic environments around 400 million years ago and have prospered ever since. From fossil records, they have been recorded from the coal making Carboniferous period (over 300 million years ago), growing to 1½ metres in length.

Centipede from the genus Cormocephalus

This group of centipedes can live for around 6 years and have developed an unusual nursing habit, whereby they wrap their body around their eggs and later, the defenceless young, where they will remain until their first moult. It is thought that the mother may provide them with their first meal by allowing them to feed from her body. After this period the mother usually dies and the young disperse. The main predation of centipedes is during their first few moults, when they are likely to be taken by spiders and carnivorous insects, but after that stage their main predators are other centipedes.

Despite their fierce reputation, there are always those who cannot resist a photo opportunity with them. Such is the case with this preying mantis.


Now for a little centipede horror story. A number of years ago during winter, I was on a camping trip to Central Australia. Although the days are pleasantly warm, the nights can be bitterly cold, so like most people we built a nice fire to sit around and socialise. Someone had placed a large log on the fire and the lady next to me was relaxing, with her legs resting upon it. All of a sudden clutching her leg, she jumped up screaming and began frantically pulling off her clothing. It turned out that a very big centipede (over 6" in length) had vacated its home in the burning log and took off up her trouser leg.

The sharp claws on its legs had perforated the shin and when she grabbed it from outside her trousers, it had bitten her savagely, injecting much venom. After a few hours she had recovered her composure, plus with some first aid had patched up her wounds, but for the rest of the trip, she never once rested her legs on wood (regardless of size) and always tucked her trouser legs into her socks. So be warned, although the Australian species are not life threatening, it is an experience well worth avoiding.


Despite the horror stories, these animals do not go out of their way to attack people, so if you accidentally come across one, let it go about its business as like all main predators they perform a major function in the ecosystem.


My thanks to the Australian Museum (Sydney) for the identification and sundry information.

8 comments:

buffy said...

I've not seen one as big as 6 inches, but I think about 4 inches in South West Vic. No idea which one it was though. And after sitting on Mt Rouse watching Comet McNaught the other night, I swung the torch around to stand up and discovered a very busy little (about an inch long) centipede scrabbling around beside me. And I didn't have the tucked in clothing thing going either! I let it go about its business.

Esperance Blog said...

Hi buffy, the ones around me are around 4 inches too. Those in the UK are apparently only around 1 inch, so maybe the cooler southern areas are not ideal for year round growth.

Thanks for the interest.

Jack.

Woollybutt (Peter) said...

Hello there Jack,

Was starting to wonder if you were posting this week.

I remember the centipedes I saw as a kid in Adelaide, dark green in colour and bigger than any others I've seen anywhere else since (I'd like to say they were six inches long, but that may be from a child's memory, although I'm not exaggerating much I wouldn't think).
I did a bit of a Google as I was viewing your blog and found a good CSIRO site for centipede ID using dichotomous keys

http://www.ento.csiro.au/biology/centipedes/centipedeKey.html

Apologies if you already knew this site, but may be useful.

See you next week,

Cheers
Peter

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Esperance Blog said...

Hi Woolly, yes its funny how our memories play tricks on us, particularly concerning the length of little things, I suppose it might be a blokey thing.

Thanks I do have that centipede key. I find that unless you have the actual animal (preferably inactive), then they are not very effective (which is one of the problems when trying to id things from photos). Still it usually gets you heading in the right direction, which is often all you need.

Thanks
Jack

Anonymous said...

hello fellow centipede lovers!!!
We were extremely excited when we found one of these centipedes. He's exactly 5" and we were pleased to discover this site whilst trying to research the centipede in question.

thanks for the wonderful information! :)

James & Lee (new centipede lovers)

Anonymous said...

hello fellow centipede lovers!!!
We were extremely excited when we found one of these centipedes. He's exactly 5" and we were pleased to discover this site whilst trying to research the centipede in question.

thanks for the wonderful information! :)

James & Lee (new centipede lovers)

Esperance Blog said...

Hi James and Lee,
Glad you found my site and it proved useful for you. The world of invertebrates is vast and intriguing requiring a lifetime to explore only a small portion. Its a great time of the year to begin, so thanks for your interest and here's wishing you both happy hunting.

Jack.

vivian said...

I bet it doesn't even matter how painful the bite was, really. What is probably more traumatizing was witnessing one of THOSE monsters on your person. That sight alone would scar me for life. But then again, I do have a phobia of centipedes, so my fear may be worse than others'.