Some organisms have location-dependent sex
determination, meaning the organism becomes
male or female depending on where it ends up.
Take the slipper limpet, for example. Slipper lim-
pets (otherwise known by their highly sugges-
tive scientific name of Crepidula fornicata) have
concave, unpaired shells and cling to rocks in
shallow seawater environments. (Basically,
they look like half of an oyster.) All young slip-
per limpets start out as male, but a male can
become female as a result of his (soon to be her)
circumstances. If a young slipper limpet settles
on bare rock, it becomes female. If a male
settles on top of another male, the one on the
bottom becomes a female to accommodate the
new circumstances. If a male is removed from
the top of a pile and placed on bare rock, he
becomes a she and awaits the arrival of a male.
After an individual becomes female, she’s stuck
with the change and is a female from then on.
Some fish also change sex depending on their
locations or their social situations.
Blue-headed
wrasse, large reef fish familiar to many scuba
divers, change into females if a male is present.
If no male is around, or if the local male disap-
pears, large females change sex to become
males. The fish’s brain and nervous system con-
trol its ability to switch from one sex to another.
An organ in the brain called the hypothalamus
(you have one, too, by the way) regulates sex
hormones and controls growth of the needed
reproductive tissues.
To add to the list of the truly bizarre, a para-
sitic critter that lives inside certain fish has an
unusual way of changing gender: cannibalism.
When a male Ichthyoxenus fushanensis, which
is a sort of parasitic pill bug (you may know the
isopod as a roly-poly), eats a female (or vice
versa), the diner changes sex — that is, he
becomes a she. In the case of the isopod, the
sex change is a form of hermaphroditism where
the genders are expressed sequentially and in
response to some change in the environment or diet.
determination, meaning the organism becomes
male or female depending on where it ends up.
Take the slipper limpet, for example. Slipper lim-
pets (otherwise known by their highly sugges-
tive scientific name of Crepidula fornicata) have
concave, unpaired shells and cling to rocks in
shallow seawater environments. (Basically,
they look like half of an oyster.) All young slip-
per limpets start out as male, but a male can
become female as a result of his (soon to be her)
circumstances. If a young slipper limpet settles
on bare rock, it becomes female. If a male
settles on top of another male, the one on the
bottom becomes a female to accommodate the
new circumstances. If a male is removed from
the top of a pile and placed on bare rock, he
becomes a she and awaits the arrival of a male.
After an individual becomes female, she’s stuck
with the change and is a female from then on.
Some fish also change sex depending on their
locations or their social situations.
Blue-headed
wrasse, large reef fish familiar to many scuba
divers, change into females if a male is present.
If no male is around, or if the local male disap-
pears, large females change sex to become
males. The fish’s brain and nervous system con-
trol its ability to switch from one sex to another.
An organ in the brain called the hypothalamus
(you have one, too, by the way) regulates sex
hormones and controls growth of the needed
reproductive tissues.
To add to the list of the truly bizarre, a para-
sitic critter that lives inside certain fish has an
unusual way of changing gender: cannibalism.
When a male Ichthyoxenus fushanensis, which
is a sort of parasitic pill bug (you may know the
isopod as a roly-poly), eats a female (or vice
versa), the diner changes sex — that is, he
becomes a she. In the case of the isopod, the
sex change is a form of hermaphroditism where
the genders are expressed sequentially and in
response to some change in the environment or diet.
No comments:
Post a Comment