I am certainly no expert, but I have been a bit involved with albinism in
captive bred corn snakes (Elaphe guttata).  As it turns out, albinism is a
bit more complex in snakes than it is in mammals.  So this may also hold
true for mollusks.  The standard corn snake is yellow with red blotches
partially outlined in black.  There are at least five types of "albinism" in
this species (with variations within some types).

The first is amelanism, the relatively common mutation where the pigment
melanin is absent.  This is the typical or true albinism of mammals (white
hair, pink skin, pink eyes) because melanins are the primary pigments that
contribute to hair, skin, and eye color in mammals.  But snakes with
amelanism, while loosing all dark pigmantation (the melanins), will retain
the yellows and reds.  Thus we have a corn snakes with red eyes and a red
and yellow body pattern - lacking black.  They are technically albinos, but
they are certainly not white.

The second type of albinism in corn snakes is hypomelanism, a reduction of
the melanistic pigments rather than a total elimination of these pigments.
Such a snakes will lack most dark pigmantation and will look very much like
an amelanistic snake, except it will have black rather than red eyes.  In
rat snakes that are originally black and white, this may result in a white
snake with blue eyes.

The third type of albinism (in reptiles at least) is anerythrism, the loss
of the red and yellow pigmentation (the principal pigment of cells called
xanthophores).  These snakes are black and white versions of the original as
the melanistic pigments are retained while the reds are lost.

The forth type of albinism is the combination of both amelanism and
anerythrism, or the loss of both the black (melanistic) pigments and the
yellow and red (xanthrophoric) pigments.  This results in a white snake with
red eyes.  This snake looks like the "standard" albino we think of, but it
is a more complex trait than is true with "albino" mammals.  This color
morph involves both the recessive amelanism gene as well as one or more
other genes.

Finally, the fifth type of "albinism" is melanism, or the abundance of the
dark pigment melanin.  This has not been seen in corn snakes (to my
knowledge) but is found in many other reptile species.

The kicker to all of this is variation within each category.  While
amelanism appears linked to a single recessive gene and is thus like a light
switch - on or off; the others are more complex and variable with a mix of
responsible genes.  It may also be that the story of albinism in mollusks is
more complex than we tend to think.

Tom Eichhorst in New Mexico, USA (yes the magazine was delayed but is in the
mail!!)


> -----Original Message-----
> From: Conchologists of America List [mailto:[log in to unmask]]On
> Behalf Of Andrew Grebneff
> Sent: Saturday, October 25, 2003 10:43 PM
> To: [log in to unmask]
> Subject: Re: Strombus pugilis albinos
>
>
> >It is not a real albinos, as the lip and the canal of the specimen are
> >colored. I remember the animal was rather pale, but not white.
> >
> >For those who are interested, here is a link to some pictures of my
> >"albinistic" S. pugilis, with a normal one (found in the same place) for
> >comparaison : <www.zonatus.com/Pugilis.htm>
>
> Actually, when I think about it, true albinos are not necessarily
> entirely unpigmented. Albino cats "often" (as if they are common!)
> have some hair pigments... tigers with black stripes, for instance,
> and have blue eyes (with red eyeshine... making me think that Siamese
> and other "Foreign" pussies and pussas have albinistic genes).
>
> Does anyone know an expert on albinism?
> --
> Andrew Grebneff
> Dunedin, New Zealand
> 64 (3) 473-8863
> <[log in to unmask]>
> Fossil preparator
> Seashell, Macintosh & VW/Toyota van nut
> _________________________
> I want your sinistral gastropods!
> _________________________
> Q: Because it reverses the logical flow of conversation.
> A: Why is top posting frowned upon?