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Marine Monday: Valentine's Edition

spanish dancer eggs

A Spanish dancer's eggs, also known as a "sea rose." [Via Wikimedia Commons]

Happy (almost) Valentine’s Day!

Here on land, we give our sweethearts flowers to show our love. But what is the undersea equivalent of a rose? To answer that question, we’ve chosen three undersea creatures who seem to embody the spirit of Valentine’s Day.

Spanish Dancer

A Spanish dancer is a nudibranch, or sea slug, but these are much prettier than our above-ground slugs. They are free swimmers and wouldn’t make this list if it weren’t for their egg sacs, which are literally called a “sea rose.” And that’s exactly what they look like, a little rose growing under the sea.

But even the adults get in on the Valentine action, often colored bright red or pink and gracefully moving through the water like flamenco dancers. Watch out, though, because Spanish dancers and their sea roses are both toxic and best admired from a distance.

Mediterranean Red Coral

Mediterranean red coral is made of a hard red or pink skeleton, covered in small polyps that wave graceful tentacles. Its bright red color is truly eye-catching; so much so that people have been harvesting it for centuries to display and make into jewelry. It’s now difficult to find a thriving colony of red coral, and thus it should be off-limits as a Valentine gift. But taking your valentine on a dive to see some living coral would make for a lovely (albeit expensive) date.

Passion Flower Feather Star

We just love the name of this creature. The passion flower feather star is an echinoderm, like a starfish. They have many feathery arms—up to 20!—that look like red petals. They grip onto rocks or other hard surfaces and use the feathery appendages on their arms to trap plankton and other small foods. They mostly stay where they are, like a flower constantly in bloom, but will curl up into a protective ball if disturbed. They add a lovely spot of color to reefs and bays in southern Australia.

Our conclusion? Undersea gardens are just as beautiful as our rose gardens on land, but they are best left alone—like a rose, these creatures will not last long out of their habitats.

To learn more about exotic and unusual sea creatures, check out our marine wildlife encyclopedia.

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Marine Monday: Antarctic Krill

What do blue whales, penguins and salmon have in common?

They all have the same diet. Much of the ocean is fed by a two-inch crustacean: krill. Antarctic krill congregate in huge masses in the Southern Ocean, dense enough to fill the belly of a blue whale, the world’s largest animal.

Penguins will march hundreds of miles to feast on krill, building up blubber that will help them survive their cold months on land. Even flying seabirds will dive in and partake of the abundance.

Without this tiny creature, the ocean would starve. But like so much else in the ocean, krill’s future is in danger. It is also a popular food for salmon, giving the fish’s meat that distinctive pink color. When humans build fish farms for predatory fish like salmon, we need to feed them. And that means that humans are now fishing krill to feed our farms, taking away potential meals from whales, penguins, and other wild creatures.

Oceana is working to prevent the overfishing of krill and the other small creatures that keep the oceans’ food chain going. To learn more about marine animals like Antarctic krill, visit our marine wildlife encyclopedia.

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Marine Monday: Tasseled Wobbegong

tasseled wobbegong

Image via Wikimedia Commons.

Some sharks are fearsome predators, all sharp teeth and angular fins. These are the sharks that inspire epic monster movies and give the word “shark” its fearsome connotations.

And then there are sharks that look like a pile of seaweed. The tasseled wobbegong is a flat reef-dwelling shark with leafy tentacles and a name that’s just as ridiculous as its appearance.

But appearances can be deceiving. The tasseled wobbegong settles down on a rock or reef, blending in perfectly with the sand and seaweed. When a tasty fish swims by, the shark comes to life, opening its jaws full of sharp, respectable teeth and snapping the poor swimmer up. Its tasseled face may look rather silly, but this shark is just as efficient a predator as its more fearsome brethren.

Sadly, we don’t know much about the tasseled wobbegong, but we do know that this sneaky hunter is in trouble thanks to overfishing and the destruction of the reefs it depends on.

Oceana is committed to protecting the habitats of tasseled wobbegongs and all the other strange and mysterious creatures of the deep.

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Marine Monday: Olive Sea Snake

olive sea snake

An olive sea snake in Australia. [Image via Wikimedia Commons]

When you think of ocean animals, snakes are not usually the first thing to come to mind, but they live as comfortably underwater as they do on the ground. Today’s Marine Monday features one of these swimming snakes, the olive sea snake.

Olive sea snakes live in corals in the waters above Australia. Divers should be cautious around these olive-brown snakes, as they will swim right up to anything that catches their curiosity, and they will bite if they feel threatened. An olive sea snake bite is venomous and can be fatal.

But don't worry, beachgoers have little to fear from this snake. Olive sea snakes live and hunt within their own small territories in coral reefs and rarely enter open water.

One cool thing about olive sea snakes is that they have a nine-month gestation period and give birth to live young, just like us! But their babies come in litters of five and are the size of a human finger, plus they grow up to be venomous sea snakes, so the similarities end there.

Want to learn more about cool marine creatures? Check out Oceana’s marine encyclopedia.

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Marine Monday: Giant Clam

Image via Wikimedia Commons.

There’s a lot more to clams than clam chowder. Sure, they just look like a hinged shell with squishy stuff inside, but make them a little bit bigger—or a lot bigger—and you can see how complex they actually are.

We don’t even need science fiction to do it. The giant clam can grow up to five feet long. Unsurprisingly, it’s the world’s biggest bivalve. It lives on reef flats and shallow lagoons in the Indo-Pacific, and it’s one of the most amazing clams you could ever hope to see.

Like its smaller cousins, the giant clam is a filter feeder, surviving off of small particles in the water. But it also has another trick up its shell. It farms out algae inside its shell, giving the big bivalve a constant flow of nutrients.

The giant clam is immobile, but luckily its soft body is safely incased inside its huge shell. Sometimes larger clams can’t close their shells all the way, which gives us a glimpse of their surprisingly colorful—and beautiful—body linings, called mantles.

You can learn more about giant clams and other cool creatures from Oceana’s marine wildlife encyclopedia.

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Marine Monday: Stalked Jellyfish

A stalked jellyfish. [Image via Wikimedia Commons.]

You’ve probably seen pictures of jellyfish floating gently through the water, but did you know that some jellyfish spend most of their lives in one spot?

Stalked jellyfish, which are funnel shaped, with eight legs joined by membranes surrounding a mouth, are one example. Only an inch or two tall, they live in cold shallow water in the North Pacific.

When stalked jellyfish mature, they attach themselves to a piece of seaweed or eelgrass with an adhesive disk. Scientists believe they might be able to basically cartwheel short distances, but for the most part, they are sessile – meaning they stay in the same place.

Because stalked jellyfish can’t follow prey, they use their tentacles to catch small fish and shellfish, although they have to spit out shells, as they’re too difficult to digest.

Although adult stalked jellyfish cannot eat large prey, immature jellyfish, called planula, have developed a collaborative approach to offer more dining options. At this point in their lives, the jellyfish are mobile, so while they can’t kill by themselves, they can gang up on rotifers, nematodes, copepods, and other ocean snacks.

Stalked jellyfish are also notable for having relatively developed nervous systems compared to their relatives.

You can learn more about stalked jellyfish from Oceana’s marine wildlife encyclopedia.

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Marine Monday: Giant Tube Worms

Image via Wikimedia Commons.

When giant tube worms were discovered in the 1970s, they were like nothing that had ever been seen before, and scientists still find them fascinating.

That’s because they live in some of the harshest environments and, unlike almost all kinds of life on Earth, do not rely on the sun for energy. Most life on the planet relies on energy from the sun, mediated by phytoplankton and plants that convert carbon dioxide into sugars. But not in deep-sea vent communities.

Giant tube worms live in the Eastern Pacific Ocean more than a mile underwater. The ocean floor here is geologically quite active, and vents are forming and closing regularly. When a new vent forms, giant tube worms are among the first species to colonize the area, and their population can reach several thousand adult worms in a couple years. The worms form long tubes out of chitin, the same material that makes up the exoskeletons of insects, crabs, and lobsters

Larval worms will float through the ocean until they find an area that is chemically appropriate to settle down in. As larvae, the worms have mouths and digestive tracts, but these are lost once they settle down and develop. Instead, adults have a large sack that holds symbiotic chemosynthetic bacteria. These bacteria oxidize sulfur produced by the vents, providing energy for the worm.

You can learn more about amazing giant tube worms from Oceana’s marine wildlife encyclopedia.

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Marine Monday: Bignose Unicornfish

bignose unicornfish

The bignose unicornfish. [Image via Wikimedia Commons]

The bignose unicornfish gets its name from its large, rounded nose, but you might be disappointed to learn that this fish doesn’t have a horn.

Others, like the spotted unicornfish, have a clear horn, and some, like the whitemargin unicornfish, have at least a stubby horn. The bignose unicornfish is also a member of the surgeonfish family, which means it has ‘cutting keels,’ or perpendicular bony plates near its tail that can act as knives to protect the fish.

This fish is typically yellow-brown, although it can change color when being groomed by a cleaner wrasse. It also has a long blue hair attached to each end of its tail.

The bignose unicornfish lives in deep reefs in the Eastern Indian and Western Pacific Oceans. Although they are typically found alone or in pairs, these fish sometimes form larger groups while feeding on zooplankton.

These fish are widespread and not facing any serious threats, though they are occasionally eaten and are caught for inclusion in aquaria. Even better, they have seen population increases in and near marine protected areas, where fishing and other harmful activities are severely regulated.

Learn more about the bignose unicornfish and other fascinating animals at Oceana’s marine encyclopedia.

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Marine Monday: Crown-of-thorns Starfish

crown of thorns starfish

Image via Wikimedia Commons.


The crown-of-thorns starfish is named for the brightly-colored spikes that coat its legs. This starfish can grow up to 16 inches across and has between 12 and 19 legs instead of the usual five -- that’s a lot of spikes!

These spikes hold poison that can cause temporary paralysis at the sting site and nausea in humans. Like other starfish, the crown-of-thorns can regrow arms. At the end of each of these arms is an eyespot that can detect light and darkness, although not color or shape.

Crown-of-thorns starfish are avid eaters of coral, and just one starfish can eat 13 square miles of coral each year. In order to eat the coral, the crown-of-thorns starfish pulls its stomach out of its body to cover the coral, then feeds through tiny hairs called cilia. All that remains of the coral is its white skeleton. Despite being voracious eaters, crown-of-thorn starfish can survive food shortages of up to six months by living off reserves.

Since the 1970s, plagues of crown-of-thorn starfish have been occurring more and more frequently, particularly in Australia's Great Barrier Reef. Scientists are still debating whether these are natural or have been caused by overfishing crown-of-thorn predators.

There aren’t many creatures interested in such a prickly snack, but a few mollusks and fish like the giant triton and the titan triggerfish play important roles keeping crown-of-thorn starfish populations under control.

Learn more about the crown-of-thorns starfish and other fascinating animals at Oceana’s marine encyclopedia.

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Marine Monday: Narwhal


Image via Wikimedia Commons.

Who doesn’t love the unicorns of the sea?

Narwhals, like dolphins and whales, are cetaceans, although they are found almost exclusively in the Arctic Ocean. Because narwhals spend so much time in icy waters, about a third of their weight is blubber to stay warm.

Narwhals are known for their unicorn-like tusk — which is actually a tooth! All narwhals have two teeth, but in most male narwhals, one of these teeth grows through the upper lip and can be as long as ten feet. Sometimes males will have two tusks or none, and occasionally females grow tusks.

Scientists aren’t quite sure why narwhals grow tusks. One idea is that males use them to prove their worth as mates and compete with other males. Another theory is that narwhals use their tusks to skewer food or mix up bottom sediments, but this doesn’t explain why female narwhals typically don’t have horns.

Just like human teeth, narwhal tusks contain blood vessels and sensory tissue—but on the outside of the tusk, so other scientists think they may be used to figure out where ice is forming, how salty water is, or what prey is nearby.

Narwhals eat squid, octopus, fish, and shellfish. Because they have only two teeth (and one usually can’t be used to chew), they usually swallow their food whole. They have also developed a special hunting technique that uses suction and water jets to pull fish and mollusks off the seafloor.

These mammals can live for as long as 50 years. They spend most of their time in small groups of less than ten narwhals, typically of only one gender, but these small groups can join forces in herds of hundreds.

Scientists believe there are about 80,000 narwhals in the Arctic right now, but are not sure whether these animals are thriving. In addition to subsistence hunting by Inuit for their skin and blubber, narwhals are also hunted for their horns. And climate change could cause serious disruptions to their lives, which are based around pack ice.

Learn more about narwhals and other fascinating sea animals at Oceana’s marine encyclopedia.

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