Sea fireflies are totally unrelated to the fireflies on land, in
spite of their name. They are crustaceans and have no backbone. V. hilgendorfii is a small
animal, only 3 mm long, roughly the size and shape of a sesame seed. The female
tends to be larger than the male. It is nocturnal and lives in the sand at the
bottom of shallow water. It is both a scavenger and a predator, mainly dining
on sandworms and dead fish.
V. hilgendorfii is produces a blue-colored
light by a specialized chemical reaction of the substrate luciferin and the
enzyme luciferase. It is indigenous to the water off of the southern Japanese
coast. V. hilgendorfii is known to the Japanese as “umihotaru”
– “umi” means sea and “hotaru” means firefly.
Dried
sea-fireflies were sometimes used as a light source by the Japanese army during
World War II to read maps in the dim light. The primary structure of the
mitochondrial DNA of V. hilgendorfii was sequenced in 2004 by two Japanese scientists, Katsunori Ogoh and
Yoshihiro Ohmiya.
V. hilgendorfii has a beaklike projection on the front of a smooth, oval,
clear carapace. The black eyes are visible through the carapace. The carapace
has large notches through which the antennae stick out. The appendages at the
tip of the abdomen are very large and visible between the folded halves of the
carapace.
V. hilgendorfii remain buried just under the surface of the
sand during the day. At night they use their antennae to move across the bottom
or swim over the bottom. When threatened they will use the large appendages on
the tip of the abdomen to push themselves into the sand. They also use these
structures to lift themselves quickly up from the sand and into the water.
Males
hold females for about 30 to 60 minutes before mating actually begins. Males
transfer a packet of sperm to the female's reproductive organs. Females brood
their eggs under the carapace. The larvae molt five times before reaching
adulthood. Young larvae are capable of crawling, digging, and swimming.
No comments:
Post a Comment