Shells of the Family Bursidae are commonly known as Frog Shells. I had always thought that this was because of the frog-like 'mouth' on the left part of the shell in the top photograph. To me, it really does look like a frog's mouth. However, I have since discovered that they are really so named because of the knobbly structure of the shell of most of the species of this family. The shell is supposed to look like the warty skin of some frogs and not all Frog Shells have that froggy 'mouth.'
Authorities vary greatly in the number of species in the Family Bursidae; I have read some books on seashells that limit Frog Shells to thirty species while others claim that there are over ninety.
One thing is certain, these shells are unusual and very popular with shell collectors. Incidentally, probably all conchologists are shell collectors, but not all shell collectors are conchologists. Conchologists are marine biologists and zoologists who specialize in studying mollusks. That is different from people like me who enjoy collecting them and delight in the wonderful colours, shapes and variety of this facet of God's wonderful creation.
Some Interesting Facts about Frog Seashells
Collectors of Frog Shells and mollusks in general may be interested in the following facts.
- Size: Mature Frog Shell mollusks vary in size from half an inch to ten inches, according to their species and they vary considerably in their appearance, as well. Like members of the Triton family to whom they are closely related, the females are larger than the males.
- Habitat: Frog Shells are most commonly found in the warmer temperate and tropical waters of the Indo-Pacific, the largest and richest shell region in the world, extending from the shores of East Africa to Polynesia. Frog Shells are mostly shallow water dwellers and live among rocks and coral in both inter-tidal and off-shore waters. Shallow water species have rounded, knob-like ridges. However, some species live in deep water and the ridges on these shells are usually sharp and blade-like.
- Diet: Frog Shells are carnivorous and feed on marine worms, and other shells including both mollusks and bivalves.
- Reproduction: Like most mollusks, they lay eggs that are sometimes produced in long strands and these are attached to rocks and coral.
- Camouflage: The larger Frog Shells camouflage themselves with a heavy calceous covering to provide protection from other marine predators.
The Shell Pictured Below
The shell pictured below has the knobbly shell and the frog-like 'mouth', but I have been unable to find it in any of the literature. I have seen some pretty orange mollusks in the Philippines, so I may have collected it there.
The shell below is about 1½ inches long and very attractive. If you happen to know its family and species, please let me know. I would be very grateful.
A Final Fact
The Giant Frog Shell (bursa bubo) sometimes grows up to ten inches, is found in both the Indian and Pacific Ocean areas and is moderately common near coral reefs. It was once used for oil lamps.