Saturday, July 21, 2007

Atlantic Calico Scallop and Florida Fighting Conch

The Calico Scallop Argopecten gibbus (Linnaeus)
Is a bivalve ranging in size from 1-3 inches. It is almost circular in shape and has equally sized ears. The exterior of the right valve is white-yellowish and usually splotched or striped with colors of red or purple. The left valve is darker in color usually with red, orange or purple variegated with white or yellow- white. This scallop is commercially fished especially off both North Carolina and eastern Florida coasts. It is found only in the ocean and lives in 100 foot depths from Delaware to Brazil.
The live scallop has rows of eyes each having its own lens and retina, but it has no center of vision in its brain and probably can't form an image. It can however distinguish light and dark. It moves by opening and closing its shell. The dark variegated scallops are also calico but a chemical reaction occurred in these shells in which the calcium carbonate had been replaced with iron sulfide when the scallops were buried in the offshore muck and lacked oxygen.(Florida's Fabulous Seashells - Williams/Carmichael)
Florida Fighting Conch Strombus alatus (Gmelin)
is 2-4.5 inches and is a thick shell and is yellow-brown to reddish brown in color often with pale spots or stripes. It's axial ribs are crossed by spiral cords and gradually become larger and more separated and knobbed. It has a stromboid notch on its lower end of the canal. This notch is typical of all true conches - hence, they are in the family of Strombidae.
A herbivore, it feeds on red algae and is found offshore from North Carolina to Texas and Mexico. Like the Atlantic Calico Scallop above, it is also commercially fished chiefly for steaks, chowders and salads.
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Wednesday, July 18, 2007

Common Paper Nauttilus, Cross-Barred Venus

The Common Paper Nautilus or Common Paper Argonaut is not really a shell in the true sense of the word. It is actually an egg case secreted by two arms of the female Argonauta argo (Linnaeus). Most shells will be secreted by the mantle of the mollusk, but not this one. I found this in the sargasso grass on Del Rey Beach, Florida on a recent trip there.
The animal is in the class Cephalopoda which is composed of the squid, octopus and nautilus. Most are predatory carnivores.
Only the female secretes the shell, the male Argonaut is much smaller and does not have a shell. They are usually found in tropic or temperate seas. The female can grow to the length of 2 feet and produce a shell as big as 14 inches long, these are nowhere near that size. They swim near the surface of the water and prey upon pteropod mollusks and small pelagic fish. Sailfish in turn, prey upon them.

Cross-Barred Venus, Chione cancellata (Linne) are one of the most plentiful shells on the island. They seem to come in a variety of colors depending on the sediment in their environment. They are heavy with strong, raised concentric ridges and rounded ribs that form a network of raised lines. Found in shallow waters, they are the main food source of the green and blue crab as well as moon snails. When you come across some with 'ready made holes for stringing', those have been likely drilled by the moon snail.
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Monday, July 16, 2007

Seashore Creatures - Cannonball Jellyfish and Portuguese Man-of-War

Cannonball Jellyfish (Stomolophus Meleagris) Class Scyphozoa
I hadn't gotten around to putting these on the blog, but I definately enjoyed finding them. On the 8th of June, there were quite a few jelly fish and a few Portuguese man-of-war on the beach, along with a lot of sargassum weed.
The Cannonball Jellyfish is 5-7 inches high and 7-9 inches wide. It floats near shore and is found from the Chesapeake Bay to Texas, the Bahamas and the West Indies. The books don't have a caution about this animal.

The Portuguese Man-of-War (Physalia physalis) is another story.
It's class is Hydrozoa and It can be found up to 12 inches long and 6 inches high by 5 inches wide. It floats by being gas filled and is iridescent blue and pink with tentacles of different lengths, some being more than 60 feet long and containing stinging cells.

The books warn that it is highly toxic and "the tentacles contain one of the most powerful poisons known in marine animals and can inflict severe burns and blisters even when the animal is dead on the beach." (National Audubon Society Field Guide To Seashore Creatures)
I'm still just learning about everything on the beach, but, I sure knew enough to stay away from this!
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Wednesday, July 4, 2007

Crenulated Pyram, Atlantic Oyster Drill, New England Basket Shell

Crenulated Pyram Pyramidella crenulata (Holmes) is a small (1/2 inch) shell with smooth, flat-sided whorls and deeply incised sutures. It's cream with tan blotches and lives in mud and in grass from the low-tide line to 50' sandy ocean bottoms. It can be found from North Carolina to Texas. It is a parasite that feeds on the soft tissues of other mollusks and marine animals.

The Atlantic Oyster Drill Urosalpinx cinerea (Say) Is a small shell measuring from 1/2 inch to 1 1/2 inch high. It's oval with an elevated spire and is grayish or yellow-white with a rough exterior with large axial ribs forming a pattern of raised wavy lines. It lives in sounds and inlets. Commonly found living in oyster reefs and on pilings. It's range is from Nova Scotia to Florida and is a carnivore that prefers barnacles and oysters. It drills a hole into the shell and feeds on the soft parts of the animal.
The New England basket shell, Nassarius trivittatus(Say) is sometimes called a threeline mudsnail, New England Dog Whelk or a New England Nassa is a small shell with a rough surface and strong axial ribbing with beaded whorls. It's between 1/2-7/8" high and is white to yellowish-gray. Southern specimens (as found in North Carolina) have 3 reddish-brown spiral bands on the body whorl. Located on sand and muddy sand and intertidally to water 300 feet deep, it's range is from Canada to Florida. It feeds on egg cases of the Northern Moon Shell and is a scavenger.
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