Starfish Keep Their Cool

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Starfish keep their cool according to an article in American Naturalist, vol. 174, pp. 890-897, 14 Oct 2009 and BBC News 28 Oct 2009. Starfish living in the intertidal zones can easily become overheated if they are left high and dry and exposed to the sun during a low tide because they cannot move until they are submerged again. A team of biologists at University of California, Davis and Bodega Marine Laboratory, Bodega Bay, California have discovered that starfish can prevent overheating by pumping cold water into their bodies in between low tides. The extra water means it takes a lot more heat from the sun to raise their body temperatures – a property of water known as “thermal inertia”.

The researchers tested the ability of the ochre starfish use the cooling property of water by keeping starfish in an aquarium where they simulated the changes in environmental conditions that occur with the tidal cycle. They found that after the starfish had been exposed to high temperatures during a simulated low tide the starfish absorbed more water during the next high tide. The scientists were impressed by the amount of water the starfish could take on board. Sylvain Pincebourde, who led the study, commented: "It's as if we decided to suck up more than 15 pounds (7 litres) of cold water in the morning to prepare ourselves for the high temperature we will get at noon. This quantity of stored water allows a decrease of almost 4°C in excess body temperature, which is enough to avoid reaching dangerous body temperatures."

The research team wrote in their report in American Naturalist: “This ability to modify the volume of coelomic (body cavity) fluid provides sea stars with a novel thermoregulatory backup when faced with prolonged exposure to elevated aerial temperatures.”

BBC

Editorial Comment: Now I as a fisherman know why some of the starfish I stand on at low tide squelch and exude water – always wondered about that. But here is the key point. Thermoregulation can only work if there is some kind of sensing mechanism that responds to changes in temperature, plus an information processing system that recognises an increase (or decrease) in temperature and sets in motion an already existing mechanism for modifying the temperature. Backup systems are a sign of advanced planning and always show the evidence of a pre-existent understanding of the bigger picture of a living thing’s circumstances than just surviving immediate threats. Such a system had to be in place before the first ever low tide exposed a starfish and the evolutionists can jump and scream all they like, but like my stood-on starfish at low tide, the facts just squash the folly of long slow purposeless change. Give God the obvious credit that is due to His name. (Ref. design, echinoderms, invertebrates)

Evidence News 22 June 2011

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