ReflectedCube.jpg, 19K
("Cube" by D. Huizer)

Anatomical Midplane:
Fact or Fiction?

(A true plane of reflection?)

How crisp is your midplane?

splitlobster.jpg, 55K
Bi-color, two-tone lobster (Homarus americanus)
(original photo by A. R. Palmer; taken at the Bonne Bay Marine Station, Bonne Bay, Newfoundland, Oct. 2008)

Most models of positional information for bilaterally symmetrical organisms refer to the 'mid-plane' as a frame of refence. To many the mid-plane may seem a convenient construct, at best an academic abstraction. The image below should dispel any uncertainty about its reality!

Although unconfirmed, this approx. 30 cm lobster (Homarus americanus) was probably a gynandromorph hermaphrodite (male on one side, female on the other). Canadian Press distributed a photograph of a similar lobster in the hands of a smiling Moncton fishmonger. It was published in many Canadian newspapers (e.g., Edmonton Journal, Sept. 25, 1997). For those deeply curious, the darker side was on the right in the second lobster photo, as was the master (crusher) claw. As more images of such lobsters have emerged, however, the side of the crusher claw appears to be independent of the side of the body that retains normal coloration.

Side of master claw (totals as of April 2010)
Side of
normal coloration
Right Left
Right 2 0
Left 2 2

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Original images and text on this page copyright (c) 1998-2010 by A. Richard Palmer. All rights reserved.
(revised Apr. 4, 2010)