CATERPILLARS ARE SCAVENGERS
animals lead precarious lives, walking on the cliff ledge of ample supplies
of food. One southern moth is walking on one of the narrowest ledges
ever discovered. Its caterpillars eat the carcass of a species protected
under the Endangered Species Act. The caterpillars of the gopher tortoise
moth dine on the shells of dead gopher tortoises.
tortoises are fascinating turtles that construct subterranean tunnels,
can live more than 30 years and, unlike most turtles, can drown if they
fall in a lake.
Alabama to Louisiana the species is federally threatened and in Florida,
Georgia and South Carolina has been recommended by some conservationists
as a candidate for the federal endangered species list.
snakes and gopher frogs, along with more than 300 different kinds of
insects have been documented to inhabit gopher tortoise burrows as safe
havens from winter cold, drought and predators. The gopher tortoise
moth has one of the most unusual relationships with tortoises yet discovered.
qualifies as a scavenger specialist. More than 90 percent of moth and
butterfly caterpillars are vegetarians, aka herbivores. The diversity
of plants they eat and the ways in which they feed on them seem near
proportion of the world's caterpillars are carnivorous, subduing and
eating other animals, including flies and spiders. Some predatory caterpillars
even eat other caterpillars, and a Hawaiian species discovered in 2005
eats snails after capturing them in a silk trap. However, aside from
herbivores, the most common caterpillar feeding category is scavengers
that make a living by eating dead animals.
tortoise moth belongs to an infamous family of scavenging moths with
which most people are familiar. These are the clothes moths whose caterpillars
eat wool and fur.
of the clothes moth family were a stimulus for the development of mothballs
to deter their laying eggs in coat closets. More than 3,000 species
within the clothes moth family have been described worldwide. The gopher
tortoise moth belongs to a group within the family whose caterpillars
are known to eat animal hooves and horns, feathers and hair.
gopher tortoise moths are among the last scavengers to arrive when a
tortoise dies and the shell is lying on the ground; the muscles, bone
and major organs have already been scavenged by flies, beetles and vertebrates.
The moths lay their eggs at night on or near the carcass, to which the
hatching caterpillars are attracted.
of interest to the caterpillars is the protein known as keratin (our
fingernails are keratin), which binds the tortoise's large shell plates
together. Keratin provides the food for the caterpillars. But what keeps
these little soft-bodied critters from becoming a meal to predatory
invertebrates, such as ants or spiders, roaming the woods?
tortoise caterpillar secretes a protective tube made mostly of silk
and covered with grains of sand that is long enough to extend from below
the ground to the various seams on the tortoise shell.
protects the creature from predators and buffers it from hot or cold
weather as it crawls to one end of the tube to eat and to the other
to retreat underground.
that are food specialists live in a state of double jeopardy. They face
the usual challenges that most animals do of finding food while avoiding
becoming food themselves in at least some stage of their life.
for the gopher tortoise moth to find a dead individual of a reptile
that lives a long time and is becoming rarer and rarer would presumably
be a major liability.
cascade is created when one species is vital to the survival of another,
for if the latter disappears the former is sure to follow. We now know
that we must protect the gopher tortoise not only for its own sake but
for that of a little moth that depends on it for survival.
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