For the First Time, Scientists Find Jellyfish-Like Animal With ‘Transient’ Anus

SaskiaAcht/iStock.com
SaskiaAcht/iStock.com

Compared to other parts of anatomy, the anus is underappreciated—but without a way to expel waste from the body, all the work that takes places at other stages of digestion wouldn't be good for much. Now scientists may have a better understanding of how the anus evolved after identifying the first "transient" anus in jellyfish, New Scientist reports.

As biologist Sidney L. Tamm reports in the journal Invertebrate Biology, the warty comb jelly (which is really a type of ctenophore, not a cnidarian like true jellyfish) doesn't have a visible anus most of the time. While studying the comb jelly, he discovered it forms one only when it needs to defecate. When waste builds up, the creature's gut or gastrodermis expands until it touches the outer layer known as the epidermis. At this point, the gastrodermis and the epidermis fuse together and form an orifice where there wasn't one before. Waste is disposed of through the newly opened anus, and once the jelly has finished its business, the hole closes up again and the gut and the epidermis go back to being two separate layers.

These two components each consist of a single cell layer, so the anal opening forms quickly. Mature warty comb jellies have to grow a new anus every hour or so, while their larvae do it about once every 10 minutes.

Jellyfish and comb jellies are simple organisms, with one inner tract instead of a more complex system of organs. Some jellies have one opening in their gastrodermis they use for eating, expelling waste, and exchanging reproductive materials. The discovery of the warty comb jelly's transient anus shows how this one-orifice system may have evolved into a tract with a permanent anus millions of years ago.

Comb jellies are some of the oldest animals on Earth, with ancestors appearing as far back as 700 million years ago. Scientists believe they helped set the evolutionary groundwork for systems that are essential to complex life today, such as the nervous system and digestive tract.

[h/t New Scientist]

Invasive Snakehead Fish That Can Breathe on Land Is Roaming Georgia

Mohd Fazlin Mohd Effendy Ooi, Flickr // CC BY 2.0
Mohd Fazlin Mohd Effendy Ooi, Flickr // CC BY 2.0

A fish recently found in Georgia has wildlife officials stirred up. In fact, they’re advising anyone who sees a northern snakehead to kill it on sight.

That death sentence might sound extreme, but there’s good reason for it. The northern snakehead, which can survive for brief periods on land and breathe air, is an invasive species in North America. With one specimen found in a privately owned pond in Gwinnett County, the state wants to take swift action to make certain the fish, which is native to East Asia, doesn’t continue to spread. Non-native species can upset local ecosystems by competing with native species for food and habitat.

The Georgia Department of Natural Resources’ Wildlife Resources Division is advising people who encounter the snakehead—a long, splotchy-brown fish that can reach 3 feet in length—to kill it and freeze it, then report the catch to the agency's fisheries office.

Wildlife authorities believe snakeheads wind up in non-native areas as a result of the aquarium trade or food industry. A snakehead was recently caught in southwestern Pennsylvania. The species has been spotted in 14 states.

[h/t CNN]

Meet Holly: The Winner of Alaska's ‘Fat Bear Week’ Competition at Katmai National Park

Katmai National Park and Preserve via Flickr, Public Domain
Katmai National Park and Preserve via Flickr, Public Domain

It's that time of year when the air gets a little colder, the days get a little shorter, and the bears get much, much fatter. Every year, in celebration of the impressive, pre-hibernation transformations of its brown bears, Alaska's Katmai National Park and Preserve hosts a competition to determine which fat bear reigns supreme. As NPR reports, Holly (a.k.a. Bear 435) is the official winner of 2019's Fat Bear Week.

In order to build enough bulk to survive the winter, brown bears must eat a year's worth of food in six months. After gobbling as much salmon as they can find, their mass typically peaks in October, which is also when Katmai holds its annual competition.

This year, the park pitted 12 coastal brown bears against each other in a March Madness-style bracket. Images of the chunky contestants were shared on Facebook, and followers cast votes for their favorite fat bears by "liking" them.

A before and after shot of Holly, winner of Katmai National Park and Preserve's Fat Bear Week competition
Katmai National Park and Preserve via Flickr, Public Domain

Holly beat runner-up Lefty by nearly 14,000 votes. The before-and-after shot above makes it easy to see why: Between July 12 and September 22, 2019, she grew from a scrawny bear into a hulking beast. The preserve announced her win on Facebook, writing: "She is fat. She is fabulous. She is 435 Holly. And you voted her the 2019 Fat Bear Week Champion. All hail Holly whose healthy heft will help her hibernate until the spring. Long live the Queen of Corpulence!"

Holly's new body is good for more than making her an internet sensation. The fatter a bear is, the more likely it is to survive the winter. But other factors, like climate change waking hibernating bears earlier than usual, still pose a threat.

[h/t NPR]

SECTIONS

arrow
LIVE SMARTER