Why some caterpillars look like **** - February 22, 2008
Japanese scientists have identified the hormone controlling a caterpillar’s amazing switch in appearance from what looks like a bird dropping to what looks like a leaf.
In the early stages of their lives swallowtail caterpillars look like unpleasant bird droppings. Later they change to resemble green leaves, before finally becoming butterflies.
Ryo Futahashi and Haruhiko Fujiwara report in this week’s Science that they have discovered the hormone that governs this change. They found that levels of ‘juvenile hormone’ decrease at the end of the bird dropping phase. Treating caterpillars with a similar compound stopped them from taking the next step and becoming leaf-mimics.
“We found that juvenile hormone works as a switch for the camouflage pattern. That is a novel aspect of this hormone,” Fujiwara, a researcher at the National Institute of Agrobiological Sciences in Japan, told Reuters.
And here’s a quote ripe for being taken out of context by intelligent design proponents. Alfried Vogler of the UK’s Natural History Museum told New Scientist the elegance of having one switch for the whole change was admirable: “If we had to design a system to do this, we would design it in the same way.”
Image top: stages of swallowtail larvae / Ryo Futahashi
Image bottom: larvae in situ / Ryo Futahashi
Comments
Any animal that uses camouflage look like to its environment. This behavior is one of adaptive Values to protect themselves against their enemies.
Natural enemies will attract to their victims or preys through chemical communication of the victim members. The victim must be supported by the way to protect themselves against such enemies. From such ways, mimicry phenomenon or camouflage. The time from receiving the stimulus until response to it is very short time although this process may be too complex to be controlled. The finding that the ability to stop the insect changing color depends on the expression of three genes: one controlling the green color, another controlling the black pigment and a third producing the spiky structures on the young animals is a good but what the actual mechanism to explain this phenomenon need to more research.
The scientist’s interest may come from searching for methods of control for agricultural pests that promote themselves in the field by mimicking plant leaves color. I hope to move toward more understanding for the actual mechanism control mimicry, but from my point Juvenile hormone is not the sole factor determining the expression of such phenomenon.
Posted by: Abdallah Samy | April 7, 2008 04:19 PM