Today's trivia looks at some of the most interesting adaptations in the Gastropod family.
As a species, Gastropoda are incredibly diverse. Only insects represent a more diverse species. This trivia hopes to cover more adaptations that some species of Gastropod have evolved to allow them to live where they do.
The familiar garden snail has evolved all the adaptations needed to live on land.
The following are some examples of the wonderful variation found in the Gastropod family.
Raft Building
This first example is known as the common purple snail Janthina janthina. This snail floats on the surface of the water by building a 'raft'. The raft is made up of air bubbles trapped in a thin layer of chitin. This allows the snail to stay afloat in the sea and feed on its preferred food, jelly fish.
A common purple snail washed ashore. Note the raft remains intact.
Common purple snail floating in water.
Net-Hunting
Perhaps even stranger is a species of Cone snail called Conus tulipa which uses its very modified mouth parts to find and envelope small fish that stay too close to it. Once captured, the snail draws in the catch and slowly digests it.
Harpoons
All members of the Conus family are predators, and another fascinating adaptation is a combination of harpoons and neurotoxin venoms. The mouthparts of the Cone snail are again highly specialised. The harpoon is held in a long tentacle like extension of its mouth which it uses to catch and paralyse small fish.
The colour patterns are a surprising camouflage - Full Size
Some species of Cone snail can have up to 100 different neurotoxins which allow the snail detect and sting the fish it wants to eat. This also makes them significant for medical research.
Image sequence showing hunting behaviour of the Cone snail
The venom of a Cone snail is exceptionally dangerous. Many species contain a complex mix of different toxins. The risk to humans handling live specimens is high. A sting from a small species might be no worse than a hornet sting. However a sting from a larger species like Conus geographus can cause fatalities with a lethal dose of 0.001-0.003mg/kg making it the most venomous creature on the planet.
Spikes
The Venus comb murex uses spines as protection against predation. This can be particularly striking and we can imagine quite a hindrance to any passing fish.
Another example of a curious spiny snail are those of the Alviniconcha genus which live in the deepest parts of the ocean by the deep sea vents.
Alviniconcha strummeri: “Because they look like punk rockers in the 70s and 80s and have purple blood and live in such an extreme environment, we decided to name one new species after a punk rock icon.”
Glow in the Dark
Cluster-wink snails like Hinea brasiliana have an adaptation which allows them to bioluminece. When something disturbs them they give off a rapid pulse of bright flashes of green/blueish light. This light is so bright that it is thought to dazzle attacking creatures like crabs.
It may also act like a burglar alarm in that it will draw the attention of larger predators which might then eat the thing bothering the snails.
This image shows examples of the clusterwink snail H. brasiliana emitting bioluminescent light
The way the shell diffuses the specific wavelength of light is surprising as it is more efficient than any commercial light diffuser.
Research: "It's rare for any bottom-dwelling snails to produce bioluminescence," Wilson said. "So its even more amazing that this snail has a shell that maximizes the signal so efficiently."
Iron Coating
The scaly foot gastropod Crysomallon squamiferum#https://en.wikipedia.org/wiki/Scaly-foot_gastropod) is an example of a snail that also lives deep in the ocean by the deep sea vents. The snail's foot is very unusual in that it is armored with iron-mineralised sclerites, composed of iron sulphides greigite and pyrite. No other animal is known to use iron sulfides in this way.
The sclerites of Kairei population is strongly magnetic due to the greigite (sulfur equivalent of magnetite) content and stick to magnets.
The snail's shell is also unusual in that is is made of three layers. Each layer is of a different material (including more iron suflide). The composition of the shell protects the snail from predators. The impact of the force of a crabs claw for example is dissipated around the shell preventing the crab from cracking open the shell.
Researcher: http://www.zoo.ox.ac.uk/group/oceans/people/CC.html
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