Sea Snakes

Sea Snakes are some of the many land animals that have adapted to live in the ocean. They seem completely out of place, yet these unusual marine reptiles are perfectly adapted for life below the waves. I'm sure it is hard to picture a snake under water, so I posted the video below of a sea snake gliding across a reef. It seems just as natural swimming underwater as it would slithering on dry land.



There are over 60 different species of sea snakes found in tropical seas throughout the world. Most are brightly colored, and nearly all sea snakes have a flattened tail that works as a paddle. Unlike their terrestrial cousins, many species of sea snakes lack the ability to crawl on land. Others are known to spend a good amount of time out of the water. Sea snakes may live underwater for most of their lives, but they still breathe air like all other reptiles.

The forked tongue of a sea snake is specially adapted to allow them to smell underwater. They cruise along coral reefs hunting fish, eels, shrimp, or even fish eggs depending on the species.

Most sea snakes are highly venomous and pack deadly poison, but few are known to be aggressive towards humans. Attacks are not very frequent, and they rarely deliver much poison when they strike. When sea snakes are handled by humans or caught on land, they can be very dangerous. As with most sea creatures, it is best to look but don't touch.

Cone Snail Videos

I was happy to see how much attention the post on Cone Snails has gotten. I understand it is hard to picture a snail killing something, so I dug up a couple of videos of these slow but deadly predators on the hunt. It's somewhat disturbing and totally amazing to see these Cone Snails in action.

This is a very good clip from National Geographic showing the full process of a Cone Snail hunting.



And this video from Nature shows how quickly a Cone Snail can subdue a live and very active fish.



One of the reader responses to my previous Cone Snail post asked where Cone Snails can be located. I found a map from National Geographic showing just this.

It's small but you can see the regions where Cone Snails can be found highlighted in yellow. They are mostly located in tropical oceans. Florida is the only place in America that I know of where you can find Cone Snails. Still, if you think you might have found a cone snail, just remember the general rule of the ocean:
When in doubt, don't touch it.

Cone Snails: Deadly Predators

Oddly enough one of the most deadly animals in the entire ocean is a tiny snail called a cone snail. While it seems comical to even think of a snail as dangerous, let alone lethal, cone snails have some of the most sophisticated and deadly neurotoxins known to man. A cone snail sting can kill a person within minutes of injection.

While most snails simply graze on algae, cone snails are active predators. They are fully capable of catching and eating quick and agile fish. These mollusks move just as slowly as other snails, but they pack a hidden weapon. They have a long tube which conceals a deadly harpoon tipped with their powerful venom. They can fire this harpoon with lightning fast accuracy. Their prey is killed almost before even knowing it has been hit. The snail then reels the dead fish into its vacuum-like mouth and swallows it whole.

People are rarely attacked by cone-snails because they do not actively hunt humans. Only about 15 known cone snail related deaths have been reported to date. Most of these incidents occur because people pick up the beautiful shells they see on the ocean floor. When the snail is agitated, it fires its harpoon, and the person often dies within minutes. If you ever see a cone-shaped shell lying on the sand, it's best to just leave it alone.

Jellyfish

Jellyfish are cnidarians, related to sea anemones and sea slugs. They consist of a dome-shaped body and tentacles that trail behind them. Jellyfish are able to swim through the water by pulsing their jelly-like bodies. Their tentacles are covered in poisonous stinging cells called nematocysts. These tentacles can paralyze or kill fish. Some jellyfish, like the box jellyfish below, are powerful enough to kill humans. The venom in a box jellyfish can stop a person's heart in less than 3 minutes.

While most jellyfish are relatively small, some can grow to enormous sizes.

During certain times of year, jellyfish can be found in huge numbers, clouding the seas with their pulsating forms.

Some jellyfish can even glow in the dark.

Sea Anemones

Sea anemones resemble flowers, but they are actually cnidarians, related to coral and jellyfish. They spend their lives rooted to surfaces using a big sticky foot. Their tentacles wave in the currents and catch any pieces of food or animals that pass by.

Sea anemones spend their larval stage as zooplankton floating in the currents. When they reach maturity, they settle on the sea bottom and anchor themselves.

The tentacles of a sea anemone are lined with tiny cells called nematocysts. These cells contain a microscopic spring loaded harpoon. When an unfortunate animal brushes by, the harpoon fires, ensnaring the victim and delivering deadly poison. Once the hapless victim is entangled, the anemone pulls it into its mouth. It digests the food in its stomach and excretes the waste back out through its mouth.
Sea anemones are often sought out as partners for other organisms which use their powerful poison as defense. Hermit crabs will often uproot small sea anemones and stick them on their backs. This serves the anemone well because it is now mobile and can more easily catch bits of food. It also gets to snack on any of the crab's leftovers. The crab benefits by having added protection from predators. Anything trying to eat the crab gets a powerful sting.

Another animal that uses the sea anemone as protection is the clown fish. These fish are adapted to keep the sea anemone from stinging them, and spend their entire lives nestled safely in their deadly tentacles.

Sea anemones come in many shapes, sizes, and colors, and can be found throughout the world, from the cold oceans of North America to tropical Australian coral reefs.