{"id":37981,"date":"2024-04-22T14:56:20","date_gmt":"2024-04-22T12:56:20","guid":{"rendered":"http:\/\/4493daa8-7690-4cc9-8e95-a38a28e56e63"},"modified":"2024-04-22T15:35:35","modified_gmt":"2024-04-22T13:35:35","slug":"discover-the-flatworm-that-can-survive-being-sliced-up-by-a-knife","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcwildlife\/rss_feed\/discover-the-flatworm-that-can-survive-being-sliced-up-by-a-knife\/","title":{"rendered":"Discover the flatworm that can survive being sliced up by a knife"},"content":{"rendered":"

Nick Baker explores the bizarre life of a freshwater flatworm <\/p>

By <\/p>

Published: Monday, 22 April 2024 at 12:56 PM<\/p>

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Stare into a pond and let your gaze fall on the silty bottom and you might notice tiny, slate-grey slithers of animal life. They\u2019re not obvious at first as, being just a few millimetres long, they are easily overlooked. Even a water flea<\/a><\/strong> oozes more charisma than a flatworm.<\/p>

But don\u2019t ignore flatworms, of which Britain has about 12 freshwater species, on account of their initial appearance. There are few pond creatures quite as bizarre as the class Turbellaria.<\/p>

What are Turbellaria flatworms and what do they look like?<\/h2>

You really will need a hand lens to appreciate the turbellarians\u2019 world of weird. The first thing to notice as you peer at their flattened form is that flatworms have a definite front end, and from the middle of their arrow-shaped head two eyes disconcertingly stare back at you. These simple eyes, or ocelli, are black but sit in a thinner window of skin, making their owners look a little boss-eyed.<\/p>

If eyes determine the front of an animal, you might expect to find an anus at the posterior \u2013 but no matter how hard you look, you won\u2019t find anything: flatworms don\u2019t have one. Search for a mouth and you\u2019ll not find that in the expected place either, for in most flatworm species it is located in the centre of the body.<\/p>

How do flatworms reproduce?<\/h2>

The most chimerical quality of flatworms, however, is how they reproduce. Among their number most are hermaphrodite: not unusual at their end of the evolutionary tree<\/a>. It\u2019s their ability to repair and regenerate that truly amazes. A myth about worms, and earthworms<\/a> in particular is that, if divided, each end will create a new animal. Sadly, it isn\u2019t the case. But it is with flatworms.<\/p>

Dice a flatworm any which way and each fragment will in time become a fully functional creature. How flatworms do this is not fully understood. But it\u2019s a quality that has given them fame for being, in the words of 19th-century naturalist John Graham Dalyell, \u201cimmortal under the edge of a knife\u201d.<\/p>

What do Turbellaria<\/em> eat?<\/h2>

The mouth is a proboscis-like arrangement, like having a hosepipe as a navel. Flatworms slowly groove away on the bottom of the pond, sucking food up through this mouth. Any waste products simply dissipate through their foliose bodies.<\/p>

There is little as sensuous as the movement of a flatworm; they seem to float, levitating across the bottom of the pond. It\u2019s an effect made possible by thousands of microscopic hairs called cilia that waft the animals along on a trail of mucous, and in doing so stir the water. Similar cilia are also used to set up feeding currents to pull food (fine detritus, algae<\/a> and protozoa) into their mouths.<\/p>

What does Turbellaria mean?<\/b><\/h3>

\u2018Turbellaria\u2019 is derived from the Latin turbella<\/i>, meaning to create a small commotion or turmoil, a name that doesn\u2019t initially seem to fit such unassuming beasts. Yet it isn\u2019t a reflection of their character, but of their ability to create a micro-storm of water currents. Many of the flatworms\u2019 other names likewise refer to their bizarre qualities. \u2018Planaria\u2019, often used to describe all free-living flatworms, means to \u2018lie flat\u2019, while \u2018triclad\u2019 refers to those species with three dead-end gut passages radiating from the central mouth.<\/p>