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I invite readers to answer a question.
Here's the question for this month:
Why does the tail of a lizard continues to
wriggle for a few moments after it has been snapped from the body? Why doesn't
the wriggling stop immediately?
I'll publish the best answers, and you get credit. Click here:
Answer-the-question
to give me your answer.
Deadline:
November 1. We will publish the best answers on November 7 (the first
Tuesday of the month).
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Chewing food with her legs Q: What animal chews its food with its legs?
(Jill,
Spartanburg, South Carolina)
 Horseshoe
crabs mating near Safety Harbor, Florida. "I
have seen them there throughout the years. One day they are there, the next day
they are all gone with only a few scattered shells of crabs that died there,"
says the photographer. Image courtesy of Roger Bansemer.
A: It's a warm, May morning along a Gulf of Mexico beach, near
Safety Harbor, Florida. Gray-blue waters lap white sand. A dark, grayish
brown shape, looking like a squished World-War II helmet, lunges along the sandy
bottom offshore. The horseshoe crab
'smells' (with millions of sensors scattered over her body) faint chemicals drifting in the water —
the pungent trace of a marine worm inching along the bottom.
Wandering, she follows the trail to the worm. Hungry, she grabs it with
her front leg-like pincers and stuffs it, live, into a hole in her esophagus
that pinch-hits as a mouth. The horseshoe crab walks, many-legged, and chews the worm. Bristly spines on walking legs
that surround the mouth grind the food with each step. The pincers poke worm parts into the mouth,
as she chews with her legs.
Video of horseshoe crabs mating, courtesy of Roger Bansemer.
The
belly side of a horseshoe crab. The bristly spines of the upper legs surround the mouth and chew the food. Photo
courtesy of Wikipedia.
The horseshoe crab, lacking jaws and teeth, usually chews its food with its legs.
It does not, however, need its legs to grind food, because like birds, "it has a
crop that breaks down food before it passes through the gut," says biologist Glenn
Gauvry of the Ecological Research & Development Group Inc. So, if some
food glides into her mouth un-chewed, it doesn't matter.
The misnamed creature, not a crab, belongs to
an ancient arthropod group existing for over 400 million years. Its
closest living relative group is the arachnids (spiders, scorpions, mites, and
ticks). Primitive and successful, the horseshoe crab's anatomy is
largely unchanged in 250 million years since trilobites roamed the Earth
— well before the super-continent Pangaea broke into today's continents.
Indeed, the horseshoe crab is closely related to trilobites. "The
trilobites became extinct, as did 50% of all animal families, 95% of all marine
species and many trees" about 250 million years
ago, but the horseshoe crab lived on.
Further Reading:
The Horseshoe Crab,
Ecological Research & Development Group
The
horseshoe crab, Marine Biological Laboratory
Horseshoe-crabs mating video by Roger Bansemer, Bansemer gallery of fine art
Horseshoe crabs by Jim Conrad
Horseshoe crabs and their extinct relatives, Palaeos.com
A guide to the order of
trilobites by M.S. Gon III, The Nature Conservancy of Hawai‘i
From
Pangaea to the present, Oregon State University
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