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Amazing Molluscan Facts
(and a bit of trivia too!!)

  • There are between 50,000 and 200,000++ mollusc species alive in the world today. Many species have yet to be discovered and many recently discovered species are yet to be identified and named.  There are, in fact, so many species of molluscs to be described as yet (i.e., not yet named by a scientist) that a handful of shell grit from deep water in places such as the Philippines may contain nearly a hundred of them (out of about 500 species for the handful, i.e.!!)
  • According to some scientists, Mollusc evolution began more than 500 million years ago, during the Cambrian period. Some of these "oldest" molluscs resembled today's chambered nautilus. (Nautilus spp - primitive Cephalopods)
  • Paleontologists use fossil shells to tell what the climate might have been like millions of years ago. This is done by comparing the fossil shells with their living relatives of today by noting where they live such as in warm or cold, and wet or dry climates.
  • All molluscs possess a fleshy mantle. Some molluscs use this mantle to produce a shell by absorbing calcium carbonate and other ingredients from their habitat and food and secreting it in an orderly fashion to form a shell house.  Molluscs keep adding to this shell and keep it under repair for its entire life.

   Why slugs have slime:
 
Slime is important for:
  • Movement: Slugs use slime, as well as suction power, to travel upside down and up trees and other vertical things. Slugs leave a slime trail behind them as they move.
  • Defense: When in danger, the slug is able to emit a thick mucus coating, and makes its body shorter and fatter. This makes it more difficult to eat them, as well as giving themselves a coating with an unpleasant taste to potential predators.
  • Water retention: Slugs can fit into almost any space due to their ability to become very long and thin or short and fat. Their slime helps them fit through a tight squeeze. They can avoid sunlight by crawling into small crevices and holes. Their slime also helps keep water in their bodies, an important factor in survival.
  • Reproduction: Mating rituals of banana slugs take place in a thick blanket of slime. Banana slugs sometimes eat each other's slime before mating!
  • Nutrition: Slugs have been seen eating slime and debris collected at their tails. It is possible that slime could have a nutritional purpose.

 

  • When we hold a large seashell up to our ear, you can hear what sounds like the waves of the seashore - because the shell echoes and jumbles all the sounds around you.  If you could listen to a shell in a completely soundproof room, you would hear nothing at all!! (the "Sounds of Silence, as it were...)
  • All cone shells possess a poisonous dart (called a "radula"), with which they harpoon, inject venom and thus kill their prey. Some cone shell possess venom is so toxic that if stung, it can seriously hurt or even kill a full-grown man! (These are the piscivorous, or fish-eating cones - they have to have a REALLY toxic poison, in order to quickly paralyze their prey - which they swallow whole, and still alive.)
  • Many land snails can lift ten times their own weight up a vertical surface. (If you were this strong, and you weighed 30 kg (about 70lb), you could carry 300kg (almost 700 pounds!!) straight up a wall!)
  • Some oysters may release over one million eggs in a season. Only about one of these eggs will survive to become an adult oyster.
  • Some oysters alternate their gender, male one year, female the next! (must make their marriages interesting!!)
  • Some members of the Scallop family  (Pectinidae) have dozens of eyes. These eyes help the scallop to detect predators, so it can either run away or clam-up!
  • Many members of the Xenophoridae shell family "collect" seashells. These shells commonly known as Carrier shells attach other shells or stones to their own shell for protection and camouflage (they look like little piles of rubble on the bottom of the ocean - and would certainly be difficult for a fish or crab to eat!!)  Some Carrier shells have been known to attach strange things to themselves - pieces of glass, bottle caps, even screws!  The most beautiful of them attach large "glass sponges" (made of silica - the same substance glass is made of!) to their shells.
  • The ocean quahog Arctica islandica L. , can live to be 220 years old.  Animals in colder water live the longest, since their metabolism is slower.
  • Boring clams can sink a ship! One of them, the misnamed Teredo Ship worm, earned its name by ruining wooden boats. In reality, it is not a worm at all, but a clam, and it can bore through a six-inch plank of wood in less than one year. They will attack any wooden structure in the waters they live in.
  • Most molluscs are capable of making pearls when foreign substances enter their shell. They coat the foreign substance with a shelly material, the same as the lining of their shell. Some molluscs can grow pearls as big as golf balls. It takes a commercial pearl oyster about two years to grow big enough to be of use to us as jewellery. The older and bigger the pearl the more valuable it becomes.  Also, pearls from molluscs that don't normally produce them are particularly valuable.  A large pearl from a Pink Conch (Strombus gigus L.) recently (in 1999) sold for over $4,000 - USD!!
  • The largest known bivalve was a  "Giant Clam" (Tridacna gigas {photos by George Sangiologlu} and {photos by Masashi Yamaguchi} Linne) which weighed in at an amazing 734 pounds (333kg!!) and was nearly four feet  (1.4m!!) in length.  The shells of this beast were often used as children's bath tubs, and for baptismal fonts in many churches.  It was once thought that the Giant Clam could trap a diver underwater by closing suddenly on his or her foot, but this could only happen to a very slow or very careless diver!!
  • The largest snail (univalve) known attained a length of nearly 800mm (two and one half feet) with a girth of over a meter!! (nearly forty inches). This trumpet conch, Syrinx aruanus Linne, weighed in at 18kg (nearly forty pounds!!).
  • The largest land snail known is the Giant African Land Snail. (Photo of a model of an Achitina fulica). It can weigh up to 2 pounds (900g) and attain a length of 15.5 inches (390mm) from head to tail.

Educators: PLEASE take the time to read this:

An important message from the US Department of Agriculture, Animal and Plant Health Inspection Service
RE: Giant African Land Snails
  • The smallest known snail shell is the Ammonicera rota (There is no "common" name for something this small!!) and measures only 0.02 inches in diameter. Fifty of them laid end to end would measure one inch!
  • Some snails live in the very tops of trees, while others live high up in the mountains or even in deserts. Some are probably living in your own back yard - wherever you live!!
  • Over 1,100 species of molluscs have been discovered living deeper than one mile (1600m) below the surface of the ocean. Ewig's Gastroverm lives at an ocean depth of about 20,000 feet, or nearly four miles (over 4500m!!). Many new species have been discovered since man has started exploring the ocean's deepest trenches, and some scientists suspect that up to a quarter of a million species may actually live in the depths of the ocean!)
  • "Pelagic" gastropods live their entire life without ever touching bottom or shore! They float and travel on the ocean's currents. The violet snail, the Janthina, can travel hundreds of miles in their lifetime as they float around on the ocean's currents. Their delicate shells only touch land when they get washed up onto beaches during storms.  The largest of these is called a Janthina (several species, all in the genus Janthina) An unsuspecting person when picking up these shells with the animal still inside they look like a piece of purple bubble gum!), will get dyed a pretty purple colour.  The animal uses this dye for protection against its enemies.
  • Some molluscs (the squids) in the class cephalopoda can rival the fishes in their swimming speed. They jet about by filling their mantle with water, and pulsing it through their siphon.
  • The common garden snail, Helix aspersa, can travel about two feet in three minutes. At that rate, it would travel one mile in five and one-half days  (now you know where the term "snail mail" comes from!!!)
  • An acre of cultivated mussels (called a "bed"!) can produce 10,000 pounds of meat in a year. This is about 500 times more than an acre of pastureland can produce in terms of beef (only about 200 pounds).
  • Most molluscs can be used as a food source for man. Some of our favorites are scallops, oysters, clams and escargot (tree snails - Helix aspersa L.)  See the Man and Mollusc article for a LOT more about edible (and non-edible!) molluscs.
  • The oldest form of money known is that of the seashell. Many cultures throughout history (even a few today), used the shell as a form of barter and trade.  See the main Man and Mollusc article for a great report on this means of trade!! To see and learn a whole lot more about the edible molluscs, visit "Man and Mollusc's Data Base of Edible Molluscs"
  • The white chalky bone we hang in our birdcages come from the cuttlefish (Class Cephalopoda, genus Sepia). This is a reduced, internal shell for this mollusc (many of the Cephalopods have reduced or even absent shells.)
 Adapted from the Conchologists of America
"Fun Facts [About Molluscs]" page.

 


This is a new counter system set up by Globel on
December 01, 2002