[ARCHIVED] Coconut Crabs

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[ARCHIVED] Coconut Crabs
Topic Started: May 14 2010, 01:17 AM (4,030 Views)
Pando	May 14 2010, 01:17 AM Post #1
Obey or I'll send you to the moon Posts: 5,648 Group: Members Member #275 Joined: Feb 24, 2010 Area of expertise: Future Evolution	As the Chinese swamp of 120 MYF nears its end (got a batch ready) I've been wondering about Coconut Crabs. The coconut crab is unique among arthropods that as they went on land their gills didn't turn into body tubes, but is currently in a proto-lung. In the Postozoic it goes further and turns into a real lung, allowing them to grow bigger. What is the biggest size they are able to achieve and what diversity can they have? I'm guessing that they will be able to grow as big as a lot of vertebrates as some seascorpions (including a 7 foot long one) went on land and arthropleura existed.

Replies:
Practically Uninformed	May 15 2010, 10:56 AM Post #31
Informed enough to care Posts: 1,570 Group: Members Member #274 Joined: Feb 20, 2010 Nationality: Born in DC, bred in SC, now in NJ. A partial citizen of Tartarus Favorite Quote: "Ya gotta put the soup-drinker in the flute-lips, and shake it all up!"	What if the place where the female glues those babies develops some kind of "cubby", or some hard-shelled pouch for the young to stay in?
	You may be a king or a lil' street sweeper, but sooner or later, you'll dance with the reaper!


MitchBeard	May 15 2010, 08:02 PM Post #32
proud gondwanan Posts: 431 Group: Members Member #281 Joined: Mar 10, 2010 Gender: Male Nationality: Australian	Pandorasaurus May 15 2010, 10:23 AM What kind of movement would they have in the trees? I explained this already pando. Because their legs don't have any terminal grasping appendages they would have to hang upside down from branches like a sloth, skittering along them. This doesn't mean they would be slow as a sloth though. As for the larval problem. What if after the eggs hatch, their mother just drops them into the undergrowth below, where they spend their larval stage as detrivores in the dark damp leaf litter. Then once they have reached the adult form they spend another week or two preying on other little critters before making their way up a suitable tree to live the adult life.



Pando	May 15 2010, 08:46 PM Post #33
Obey or I'll send you to the moon Posts: 5,648 Group: Members Member #275 Joined: Feb 24, 2010 Area of expertise: Future Evolution	Oooh, I like that. How can they go quickly from branch to branch?



MitchBeard	May 15 2010, 08:58 PM Post #34
proud gondwanan Posts: 431 Group: Members Member #281 Joined: Mar 10, 2010 Gender: Male Nationality: Australian	MitchBeard May 15 2010, 06:27 AM I just had a lovely mental image of pith helmed explorers with machetes looking up into the canopy above their path watching these lovecraftian fruit skittering upside down along the highest branches at top speed and launching themselves across the gap, rotating 180 degrees so their legs face down and crashing into the trees on the otherside. The smaller ones would be able to get up a bit of speed, the ones pushing the upper limit for size would have to orang it around I suppose.



Margaret Pye	May 15 2010, 09:13 PM Post #35
Adult Posts: 596 Group: Members Member #267 Joined: Feb 3, 2010 Gender: Female Nationality: Australian	Isn't there a Jamaican land crab that lays its eggs in empty snail shells full of water, and they go through the zoea stage there? (Dunno what they eat - live off yolk? Mother comes back now and then and lays unfertilised eggs for them to eat?)
	My speculative dinosaur project. With lots of fluff, parental care and mammalian-level intelligence, and the odd sophont.


Canis Lupis	May 15 2010, 09:16 PM Post #36
Dinosaurs eat man, woman inherits the Earth. Posts: 5,881 Group: Away Staff Member #95 Joined: Oct 16, 2008 Gender: Female Nationality: United States Favorite Quote: "A speccer once tried to tell me I was wrong. I ate his liver with some fava beans and a nice Chianti."	I don't see leaping as being a good idea for a coconut crab. Exoskeletons are fragile things and any crack could be potentially life threatening. And by leaping between gaps, the chances of a serious crack are exponentially greater. Though I do like the idea of a sloth-like descendent. BTW Pando, I'd say the maximum size for any kind of terrestrial arthropod (effective respiratory system or not) would be the size of a golden retriever. Any bigger and molting would leave them EXTREMELY vulnerable.



MitchBeard	May 15 2010, 09:19 PM Post #37
proud gondwanan Posts: 431 Group: Members Member #281 Joined: Mar 10, 2010 Gender: Male Nationality: Australian	That could work. Like in a bromeliad or a dead pitcher plant or something. What do they do once they are fully developed, but still minuscule though? EDIT there are a multitude of behavioural adaptations that could develop in order to protect themselves during moulting. I agree with your size estimate though/ Edited by MitchBeard, May 15 2010, 09:22 PM.



Pando	May 15 2010, 09:23 PM Post #38
Obey or I'll send you to the moon Posts: 5,648 Group: Members Member #275 Joined: Feb 24, 2010 Area of expertise: Future Evolution	Maybe when they take their first steps on land they feed on fallen leaves and rotting carcasses, and go up from there to things like other big arthropods (more oxygen allows all arthropods to grow big) and fruits, and climb up from there. Maybe not jumping, they could grab on with their pinchers and if it's safe to go on they "jump" to it while still having the pinchers attached and cling on to the branch. The upper size I put for it would be a meter, or 3.5x bigger than they are today. Also, what kind of primates could evolve to crack open their exoskeleton?



Canis Lupis	May 15 2010, 09:29 PM Post #39
Dinosaurs eat man, woman inherits the Earth. Posts: 5,881 Group: Away Staff Member #95 Joined: Oct 16, 2008 Gender: Female Nationality: United States Favorite Quote: "A speccer once tried to tell me I was wrong. I ate his liver with some fava beans and a nice Chianti."	Any kind. So long as they can use rocks as tools.



MitchBeard	May 15 2010, 09:50 PM Post #40
proud gondwanan Posts: 431 Group: Members Member #281 Joined: Mar 10, 2010 Gender: Male Nationality: Australian	Or they could just pick them up and smash them against the ground or tree trunks. x3.5 what they are today would mean that they would have a body length of just under a metre and a half, and a leg span of about three metres, and would weigh in a 14 kilos. Thats a direct scale up though, proportions might change. Edited by MitchBeard, May 15 2010, 09:54 PM.



Canis Lupis	May 15 2010, 09:53 PM Post #41
Dinosaurs eat man, woman inherits the Earth. Posts: 5,881 Group: Away Staff Member #95 Joined: Oct 16, 2008 Gender: Female Nationality: United States Favorite Quote: "A speccer once tried to tell me I was wrong. I ate his liver with some fava beans and a nice Chianti."	True. But rocks are just better.



Pando	May 15 2010, 10:01 PM Post #42
Obey or I'll send you to the moon Posts: 5,648 Group: Members Member #275 Joined: Feb 24, 2010 Area of expertise: Future Evolution	There's already the abdominal swampman with a long snout, so they can use that. But with so much meat they can have great intelligence. Coconut Crabs are 10 inches long and can have a legspan of up to a meter, 3.5x as long will be 3 feet long with a legspan of up to 11.5 feet. Edited by Pando, May 15 2010, 10:01 PM.



Canis Lupis	May 15 2010, 10:14 PM Post #43
Dinosaurs eat man, woman inherits the Earth. Posts: 5,881 Group: Away Staff Member #95 Joined: Oct 16, 2008 Gender: Female Nationality: United States Favorite Quote: "A speccer once tried to tell me I was wrong. I ate his liver with some fava beans and a nice Chianti."	How can the swampman use its snout to get at the coconut crab meat? I still say rocks (which have been used by numerous species to crack open eggs, coconuts, and even crabs) or dropping them on the ground would be the best option to get at the meat.



Rhob	May 15 2010, 10:23 PM Post #44
Adult Posts: 527 Group: Members Member #260 Joined: Jan 20, 2010 Area of expertise: Xenobiology Nationality: Floridian Favorite Quote: "We are a way for the Cosmos to know itself." - Carl Sagan	Canis Lupis May 15 2010, 09:16 PM BTW Pando, I'd say the maximum size for any kind of terrestrial arthropod (effective respiratory system or not) would be the size of a golden retriever. Any bigger and molting would leave them EXTREMELY vulnerable. How do you figure this? What are the calculations involved?



Canis Lupis	May 15 2010, 10:47 PM Post #45
Dinosaurs eat man, woman inherits the Earth. Posts: 5,881 Group: Away Staff Member #95 Joined: Oct 16, 2008 Gender: Female Nationality: United States Favorite Quote: "A speccer once tried to tell me I was wrong. I ate his liver with some fava beans and a nice Chianti."	Just pure speculation. I'm not much for calculations. It came from when I was talking to Metalraptor, who is a biology/paleontology major. I'm not sure how we came up with it, but it makes sense to me.



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