10 Juicy Facts About Sea Apples

They're both gorgeous and grotesque. Sea apples, a type of marine invertebrate, have dazzling purple, yellow, and blue color schemes streaking across their bodies. But some of their habits are rather R-rated. Here’s what you should know about these weird little creatures.

1. THEY’RE SEA CUCUMBERS.

The world’s oceans are home to more than 1200 species of sea cucumber. Like sand dollars and starfish, sea cucumbers are echinoderms: brainless, spineless marine animals with skin-covered shells and a complex network of internal hydraulics that enables them to get around. Sea cucumbers can thrive in a range of oceanic habitats, from Arctic depths to tropical reefs. They're a fascinating group with colorful popular names, like the “burnt hot dog sea cucumber” (Holothuria edulis) and the sea pig (Scotoplanes globosa), a scavenger that’s been described as a “living vacuum cleaner.”

2. THEY'RE NATIVE TO THE WESTERN PACIFIC OCEAN.

Sea apples have oval-shaped bodies and belong to the genus Pseudocolochirus and genus Paracacumaria. The animals are indigenous to the western Pacific, where they can be found shuffling across the ocean floor in shallow, coastal waters. Many different types are kept in captivity, but two species, Pseudocolochirus violaceus and Pseudocolochirus axiologus, have proven especially popular with aquarium hobbyists. Both species reside along the coastlines of Australia and Southeast Asia.

3. THEY EAT WITH MUCUS-COVERED TENTACLES.

Sea cucumbers, the ocean's sanitation crew, eat by swallowing plankton, algae, and sandy detritus at one end of their bodies and then expelling clean, fresh sand out their other end. Sea apples use a different technique. A ring of mucus-covered tentacles around a sea apple's mouth snares floating bits of food, popping each bit into its mouth one at a time. In the process, the tentacles are covered with a fresh coat of sticky mucus, and the whole cycle repeats.

4. THEY’RE ACTIVE AT NIGHT.

Sea apples' waving appendages can look delicious to predatory fish, so the echinoderms minimize the risk of attracting unwanted attention by doing most of their feeding at night. When those tentacles aren’t in use, they’re retracted into the body.

5. THE MOVE ON TUBULAR FEET.

The rows of yellow protuberances running along the sides of this specimen are its feet. They allow sea apples to latch onto rocks and other hard surfaces while feeding. And if one of these feet gets severed, it can grow back.

6. SOME FISH HANG OUT IN SEA APPLES' BUTTS.

Sea apples are poisonous, but a few marine freeloaders capitalize on this very quality. Some small fish have evolved to live inside the invertebrates' digestive tracts, mooching off the sea apples' meals and using their bodies for shelter. In a gross twist of evolution, fish gain entry through the back door, an orifice called the cloaca. In addition expelling waste, the cloaca absorbs fresh oxygen, meaning that sea apples/cucumbers essentially breathe through their anuses.

7. WHEN THREATENED, SEA APPLES CAN EXPAND.

Most full-grown adult sea apples are around 3 to 8 inches long, but they can make themselves look twice as big if they need to escape a threat. By pulling extra water into their bodies, some can grow to the size of a volleyball, according to Advanced Aquarist. After puffing up, they can float on the current and away from danger. Some aquarists might mistake the robust display as a sign of optimum health, but it's usually a reaction to stress.

8. THEY CAN EXPEL THEIR OWN GUTS.

Sea apples use their vibrant appearance to broadcast that they’re packing a dangerous toxin. But to really scare off predators, they puke up some of their own innards. When an attacker gets too close, sea apples can expel various organs through their orifices, and some simultaneously unleash a cloud of the poison holothurin. In an aquarium, the holothurin doesn’t disperse as widely as it would in the sea, and it's been known to wipe out entire fish tanks.

9. SEA APPLES LAY TOXIC EGGS.

These invertebrates reproduce sexually; females release eggs that are later fertilized by clouds of sperm emitted by the males. As many saltwater aquarium keepers know all too well, sea apple eggs are not suitable fish snacks—because they’re poisonous. Scientists have observed that, in Pseudocolochirus violaceus at least, the eggs develop into small, barrel-shaped larvae within two weeks of fertilization.

10. THEY'RE NOT EASILY CONFUSED WITH THIS TREE SPECIES.

Syzgium grande is a coastal tree native to Southeast Asia whose informal name is "sea apple." When fully grown, they can stand more than 140 feet tall. Once a year, it produces attractive clusters of fuzzy white flowers and round green fruits, perhaps prompting its comparison to an apple tree.

14 Adorable, Vintage Photos of Rabbits

Chaloner Woods, Getty Images
Chaloner Woods, Getty Images

In honor of International Rabbit Day (held annually on the fourth Saturday of September), we've pulled photographic proof that the furry little mammals have always been appreciated by children and the adults who use a number of rabbit-related phrases and idioms more often than they probably realize.

1. DOWN THE RABBIT HOLE

Nursery school children playing with their pet rabbit Bubbles; 1939.
David Parker, Fox Photos/Hulton Archive/Getty Images

Nursery school children playing with their pet rabbit Bubbles, 1939.

2. DUST BUNNY

 A woman spinning Angora rabbit wool in her garden, 1930.
Fox Photos, Getty Images

A woman spinning Angora rabbit wool in her garden, 1930.

3. MAD AS A MARCH HARE

A young boy holds a pet rabbit, 1955.
Charles Ley, BIPs/Getty Images

A young boy holds a pet rabbit, 1955.

4. BUY THE RABBIT

A golfer makes a practice drive while his pet rabbit minds the balls; 1938.
Reg Speller, Fox Photos/Hulton Archive/Getty Images

A golfer makes a practice drive while his pet rabbit minds the balls, 1938.

5. HONEY BUNNY

School children petting rabbits; 1949.
Chaloner Woods, Getty Images

Schoolchildren petting rabbits, 1949.

6. HAREBRAINED IDEA

A woman took her Himalayan rabbit, Albrecht Durer, on a walk in Hyde Park, 1939.
Fox Photos, Getty Images

A woman took her Himalayan rabbit, Albrecht Durer, on a walk in Hyde Park, 1939.

7. CUDDLE BUNNY

A little girl petting a large rabbit, 1949.
Chaloner Woods, Getty Images

A little girl petting a large rabbit, 1949.

8. LUCKY RABBIT'S FOOT

Schoolgirls care for pet rabbits, 1932.
Fox Photos, Getty Images

Schoolgirls care for pet rabbits, 1932.

9. PULL A RABBIT OUT OF A HAT

A young magician and his rabbit, 1971.
George W. Hales, Fox Photos/Getty Images

A young magician and his rabbit, 1971.

10. SNOW BUNNY

A woman shows off her two pet angora rabbits, circa 1955.
George Pickow, Three Lions/Getty Images

A woman shows off her two pet angora rabbits, circa 1955. Angoras can be sheared to provide enough wool for two sweaters each year.

11. THE EASTER BUNNY

A little girl holds an Easter bunny on a leash, circa 1955.
George Pickow, Three Lions/Getty Images

A little girl holds an Easter bunny on a leash, circa 1955.

12. A RABBIT TRAIL

Three children hold a rabbit, 1935.
H. Allen, Topical Press Agency/Getty Images)

Three children hold a rabbit, 1935.

13. RABBIT FOOD

A boy feeds his pet rabbit a lettuce leaf, circa 1955.
George Pickow, Three Lions/Getty Images

A boy feeds his pet rabbit a lettuce leaf, circa 1955.

14. RABBITING ON

Actresses Fiona Fullerton and Clare Clifford posting some of the many letters sent to the House of Lords and parliamentary candidates to request support for World Day for Laboratory Animals which was instituted that year, 1979.
Central Press, Getty Images

Actresses Fiona Fullerton and Clare Clifford posting some of the many letters sent to the House of Lords and parliamentary candidates to request support for World Day for Laboratory Animals which was instituted that year, 1979.

Fossilized Fat Shows 550-Million-Year-Old Sea Creature May Have Been the World's First Animal

Ilya Bobrovskiy, the Australian National University
Ilya Bobrovskiy, the Australian National University

A bizarre sea creature whose fossils look like a cross between a leaf and a fingerprint may be Earth's oldest known animal, dating back 558 million years.

As New Scientist reports, researchers from the Australian National University (ANU) made a fortunate find in a remote region of Russia: a Dickinsonia fossil with fat molecules still attached. These odd, oval-shaped creatures were soft-bodied, had rib structures running down their sides, and grew about 4.5 feet long. They were as “strange as life on another planet,” researchers wrote in the abstract of a new paper published in the journal Science.

Another variety of fossil
Ilya Bobrovskiy, the Australian National University

Although Dickinsonia fossils were first discovered in South Australia in 1946, researchers lacked the organic matter needed to classify this creature. "Scientists have been fighting for more than 75 years over what Dickinsonia and other bizarre fossils of the Edicaran biota were: giant single-celled amoeba, lichen, failed experiments of evolution, or the earliest animals on Earth,” senior author Jochen Brocks, an associate professor at ANU, said in a statement.

With the discovery of cholesterol molecules—which are found in almost all animals, but not in other organisms like bacteria and amoebas—scientists can say that Dickinsonia were animals. The creatures swam the seas during the Ediacaran Period, 635 million to 542 million years ago. More complex organisms like mollusks, worms, and sponges didn’t emerge until 20 million years later.

The fossil with fat molecules was found on cliffs near the White Sea in an area of northwest Russia that was so remote that researchers had to take a helicopter to get there. Collecting the samples was a death-defying feat, too.

“I had to hang over the edge of a cliff on ropes and dig out huge blocks of sandstone, throw them down, wash the sandstone, and repeat this process until I found the fossils I was after,” lead author Ilya Bobrovskiy of ANU said. Considering that this find could change our understanding of Earth’s earliest life forms, it seems the risk was worth it.

[h/t New Scientist]

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