Nudibranchs, the Butterflies of the Sea, May Also Be Ruthless 'Kleptopredators'

Wilfred Hdez, Flickr // CC BY 2.0
Wilfred Hdez, Flickr // CC BY 2.0

There's nothing ruder than taking someone's food without asking—except maybe waiting until they're finished eating and consuming them whole so you can get those extra calories. As Gizmodo reports, this way of feeding, dubbed "kleptopredation," may be how at least one group of mollusks prefers to take its meals.

In their recent study published in the journal Biology Letters, European scientists explored the eating habits of nudibranchs. Nudibranchs are soft-bodied sea slugs that are sometimes called "butterflies of the sea" for their colorful appearances. The striking sea creatures are also effective carnivores, preying on sponges, anemones, and occasionally other nudibranchs.

For their experiment, the researchers placed members of a nudibranch species known as the pilgrim hervia (Cratena peregrina) in a tank with one of their favorite treats: hydroids, a relative of jellyfish. Plankton were also present for the hydroids to eat. When given a choice between the empty-stomached hydroids and hydroids that had just consumed or were in the middle of consuming plankton, the nudibranchs chose the well-nourished prey in 14 out of the 25 trials. According to the study authors, plankton can make up at least half of the nudibranch diet this way even though it's being preyed upon indirectly. This means that a nudibranch's interactions with a plankton-loving cnidarian could go beyond the basic predator-prey relationship.

Though the nudibranchs' preference for hydroids that had eaten plankton wasn't random, that doesn't automatically mean it's a case of kleptopredation. It's possible that the sea slugs simply chose the prey that looked larger, or they went after the hydroids that had just fed because the stinging cells the cnidarians use to hunt were worn out and therefore less harmful.

If more research does support the theory that the animals target full prey before giving them a chance to digest, that would add the unique predation method to the already impressive roster of nudibranch abilities.

[h/t Gizmodo]

Australian Island Wants Visitors to Stop Taking Wombat Selfies

iStock.com/LukeWaitPhotography
iStock.com/LukeWaitPhotography

Spending a day observing Australian wildlife from afar isn't enough for some tourists. On Maria Island, just off the east coast of Tasmania, many visitors can't resist snapping pictures with the local wombats—and the problem has gotten so out of hand that island officials are asking people to pledge to leave the cute marsupials out of their selfies.

As CNN Travel reports, the Maria Island Pledge has been posted on signs welcoming visitors to the national park. It implores them to vow to the island to "respect and protect the furred and feathered residents." It even makes specific mention of the wombat selfie trend, with one passage reading:

"Wombats, when you trundle past me I pledge I will not chase you with my selfie stick, or get too close to your babies. I will not surround you, or try and pick you up. I will make sure I don’t leave rubbish or food from my morning tea. I pledge to let you stay wild."

The pledge isn't a binding contract guests have to sign. Rather, park officials hope that seeing these signs when they arrive will be enough to remind visitors that their presence has an impact on the resident wildlife and to be respectful of their surroundings.

The adorable, cube-pooping wombats at Maria Island are wild animals that aren't accustomed to posing for pictures, and should therefore be left alone—though in other parts of Australia, conservationists encourage tourists to take wildlife selfies. Rottnest Island off the country's west coast is home to 10,000 quokkas (another photogenic marsupial), and the quokka selfies taken there help raise awareness of their vulnerable status.

[h/t CNN Travel]

Divers Swim With What Could Be the Biggest Great White Shark Ever Filmed

iStock.com/RamonCarretero
iStock.com/RamonCarretero

New pictures and video taken by divers show what could possibly be the largest great white shark ever caught on camera, CNN Travel reports.

Deep Blue, a 50-plus-year-old great white first documented 20 years ago, was spotted off the coast of Hawaii recently in a rare close encounter. Divers were filming tiger sharks feeding on a sperm whale carcass south of Oahu when Deep Blue swam up and began scratching herself on their boat. They accompanied the shark in the water for the rest of the day, even getting close enough to touch her at times.


View this post on Instagram

A post shared by Ocean Ramsey #OceanRamsey (@oceanramsey) on

"She swam away escorted by two rough-toothed dolphins who danced around her over to one of my [...] shark research vessels and proceeded to use it as a scratching post, passing up feeding for another need," Ocean Ramsey, one of the divers, wrote in an Instagram post.


View this post on Instagram

A post shared by Ocean Ramsey #OceanRamsey (@oceanramsey) on

Deep Blue is roughly 20 feet long and weighs an estimated 2 tons—likely making her one of the largest great whites alive. (The record for biggest great white shark ever is often disputed, with some outlets listing an alleged 37-foot shark recorded in the 1930s as the record-holder.)

Deep Blue looks especially wide in these photos, leading some to suspect she's pregnant. Swimming so close to great whites is always dangerous, especially when they're feeding, but older, pregnant females tend to be more docile.

Though great white sharks are the largest predatory sharks in the ocean, sharks of Deep Blue's size are seldom seen, and they're filmed alive even less often, making this a remarkable occurrence.

[h/t CNN Travel]

SECTIONS

arrow
LIVE SMARTER