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Macrocheira Kaempferi
When you think of the
worlds largest spider you will normally envisage the Tarantula, with a leg
span of 8 or 9 inches, but technically speaking the worlds largest spider
is the Taka-ashi-gani or Japanese Spider Crab, Macrocheira
Kaempferi. One specimen had a 3.7m or 12 foot leg span
and weighed 41 lb! If you bashed it with a broom, you would just make it mad ! ...and its not what you would want to find
crawling across your living room floor as this picture below
illustrates...although I can safely say that this particular one is dead and has
been propped up, otherwise there would be a house for sale!
Luckily they are not found too far inland to be much cause
for concern, but its amazing that something can grow to this size and those
pincers have a sharp row of teeth for shearing and crushing anything
unlucky enough to get corned by it.
<---------------------------12
ft------------------------->
...with legs extended.
The Japanese spider crab has 8
legs and 2 big feeding arms, and generally lives under water but has been
found on land. Many years ago when one of these was initially found
inland, in the Jungles of Japan, they naturally caused quite a stir in the
local community.
Below is a drawing of the spider crab standing next to a young
woman for scale of its actual size. Imagine finding a spider like this in
your bathtub !
The Giant Japanese spider crab can generally be found in the
Pacific Ocean around Japan. They can live at depths of 50-300m or
150-1000 feet.
They generally have a dark orange body,
with white spots on their legs. In male specimens, the limbs on
which the claws are located, become more extended than its legs. The spider crabs eyes are situated directly on
the front, and two thorns stick out between them. Younger specimens of the
spider crab feature hair and thorns on the body, and their frontal horns are
longer, but these get shorter as they grow older. Below: Could you imagine this thing crawling
across your table, whilst eating your tea.
The Giant spider crab is one of the largest arthropods know to
man. They measure up to 3.7 meters from the tip of one claw to another.
The width of their body usually grows to about 37cm (15inches) and they are
covered with little nodules called tubercles, most of their size is taken up by
their long legs. Not quite the nicest thing to see crawling up
your wall at home though. Below a 12 foot one has been made into an
interesting mural !
Giant spider crabs are
omnivorous and scavenge for food. They can eat algae, plants, molluscs and
small fish, catching and tearing up the meat in their powerful pincers. Their
long legs enable them to move quite quickly and stalk their prey. They move along the Ocean floor very slowly,
and are consequently easy targets for hungry predators, that are big enough to
attack it. As some form of protection, they attach sponges and smaller
animals to their shells to divert predators. The spider crab tends to live in Ocean vents
or holes that are big enough to take it. They are now hunted by fisherman
as their meat is apparently quiet delicious. The spider crab is caught
using trawling nets, and is often eaten salted and steamed. They are caught in
the Sagami, Tosa and Suruga bays and also around the Izu Islands. During the spring when the crab lays its
eggs, hunting them is prohibited and most fishermen thankfully obey these
rules and the spider crab will not be served as a nice dish, allowing it to
propagate so that it wont become and endangered species.
Below a guy is suitably impressed...if his expression is
anything to go by, standing next to a dead spider crab. This one is not a
fully grown one either ! " I'm coming to get ya !
"
I for one won't be swimming inshore in
Japanese waters, unless I have one of the bigger varieties of harpoon-gun with
me ! Or a big pair of rubber gloves, to hold a baby one, like this guy....
--------------------------------------------------------------- Is it a spider or is it a crab
? Your Replies. An ecology student has
recently indicated via e-mail that it is indeed from the crab family as it has
10 legs, Decapoda (dec as in 10). The feeding arms presumably have been included
in this number, but it doesn't use these 'arms' for walking//crawling on, so the
original count of eight legs still holds. As I said in my reply " If I was
to crawl on all fours would my arms be counted as legs"
Mr.
Robert Aaron Grigsby writes:
"Just wanted to point out that
the last picture you have on the spider crab page is not at all a spider crab
but an Alaskan King Crab,
Paralithodes camtschaticus.
You know this by the shorter heftier legs and the short "feeder" legs."
Mr. J. Harker writes:
"As a recent student in the zoology of
invertebrates: Mr. Mathew Allen Bhar points
out in a recent E-mail... "Actually,
there really is no dispute about whether the spider crab is a spider or a crab.
Your defense for the first message you received about crabs actually having 10
legs and not 6 like you had said, is that the forelimbs don't count as legs.
Well referring to something as X legged is generally referring to limbs that
originated as a means of locomotion along the land. All mammals have 4
"legs". Based upon your defence, it sounds as if you feel we aren't
mammals. And furthermore, by saying the pinchers "don't count", you aren't
only saying that spider crabs aren't crabs, you're also saying all crabs aren't
crabs. The "spider" part of a spider crabs name comes from the spindly
legged appearance. After all, how many spiders have pinchers and lack
chelicerae? " Another e-mail explains
the Spider is a crab as Mr. Mike Rutherford writes:
"I liked the photos you
have in the Natural World section of your website but there are a few mistakes
in some of the text. Giant Japanese 'Spider'
Crabs are definitely, 100% crabs and nothing to do with spiders at all - no
debate it's just a fact. Scorpions are arachnids but Arachnida is not a class of
insect. Both these animals are in
the Arthropoda phylum, scorpions are in the subphylum Chelicerate and the class
Arachnida, giant spider crabs are in the subphylum Crustacea and the class
Malacostraca. Insects are in the subphylum Hexapoda and the class Insecta.
I love that you have taken the time and effort to make a
great website and you obviously have a love for some weird and wonderful animals
but I just wanted to help you get the correct information out there so that if
people find your site they don't get confused. Cheers
"
Mike Rutherford
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