This sea creature breathes through its butt - Cella Wright
-
0:07 - 0:09Can you guess what you’re looking at?
-
0:09 - 0:17Is it a fuzzy sock? An overripe banana?
A moldy tube of toothpaste? -
0:17 - 0:21In fact, this is the humble sea cucumber,
and while it might look odd, -
0:21 - 0:27its daily toil paves the way
for entire ecosystems to thrive. -
0:27 - 0:31Sea cucumbers are members
of the phylum Echinodermata, -
0:31 - 0:36along with sea urchins, starfish
and other radially symmetrical, -
0:36 - 0:39“spiny-skinned” marine invertebrates.
-
0:39 - 0:42Some sea cucumbers have feathery tentacles
flowing from their mouths, -
0:42 - 0:45some are puffed like bloated balloons,
-
0:45 - 0:48and others simply look like
Headless Chicken Monsters— -
0:48 - 0:53the actual name given
to a rare deep-sea species. -
0:53 - 0:57But they are generally characterized
by their long, cylindrical shape. -
0:57 - 1:02A sea cucumber is essentially a brainless,
fleshy form surrounding a digestive tract, -
1:02 - 1:06bookended by a mouth and an anus.
-
1:06 - 1:09Adhesive tube feet
run the length of their bodies -
1:09 - 1:12and allow them to scoot along
the seafloor. -
1:12 - 1:16Specialized tube feet can be used
for feeding and respiration, -
1:16 - 1:20though many sea cucumbers actually
breathe through their anuses. -
1:20 - 1:23Rhythmically contracting and relaxing
their muscles, -
1:23 - 1:28they draw water in and out
over an internal lung-like structure -
1:28 - 1:32called a respiratory tree
that extracts oxygen from seawater. -
1:32 - 1:34Certain species of crabs and pearlfish
-
1:34 - 1:37take advantage of this
rhythmic action and, -
1:37 - 1:42once the sea cucumber’s anus is dilated,
they shimmy in and take shelter. -
1:42 - 1:49The rear end of a single sea cucumber can
harbor up to fifteen pearlfish at a time. -
1:49 - 1:51However, it seems that not all
sea cucumbers -
1:51 - 1:54put up with this intrusive behavior.
-
1:54 - 1:57Some species are equipped with five teeth
around their anus, -
1:57 - 2:01suggesting that they may have taken
an evolutionary stand -
2:01 - 2:03against unwanted guests.
-
2:03 - 2:06But even sea cucumbers
that lack anal teeth -
2:06 - 2:09are outfitted with tools
to defend themselves. -
2:09 - 2:11They evade threats
and launch counter-attacks -
2:11 - 2:15using their mutable collagenous tissue,
or MCT. -
2:15 - 2:20This gel-like tissue contains
bundles of collagen, called “fibrils.” -
2:20 - 2:24Proteins can interact with these fibrils
to slide them together, -
2:24 - 2:27stiffening the tissue, or apart,
softening it. -
2:27 - 2:30This versatile tissue has many advantages:
-
2:30 - 2:33it aids in efficient locomotion,
-
2:33 - 2:36enables sea cucumbers
to fit into small spaces, -
2:36 - 2:39and allows them to reproduce
asexually by splitting apart. -
2:39 - 2:45But MCT’s most explosive application
is employed when a predator attacks. -
2:45 - 2:48By loosening the attachments
of internal tissues -
2:48 - 2:51then quickly softening
and contracting their muscles, -
2:51 - 2:54many species are capable of shooting
a wide range of organs -
2:54 - 2:56out of their anuses.
-
2:56 - 2:58This act is called “evisceration”
-
2:58 - 3:01and it’s a surprisingly effective
defense mechanism. -
3:01 - 3:04In addition to startling
and distracting predators, -
3:04 - 3:08the innards of some sea cucumber
species are sticky and toxic. -
3:08 - 3:11Evisceration may seem drastic,
-
3:11 - 3:15but sea cucumbers are able to regenerate
what they’ve lost to their gut reaction -
3:15 - 3:17in just a few weeks’ time.
-
3:17 - 3:20Aside from the few species
that have evolved to swim -
3:20 - 3:22and those that feed without moving,
-
3:22 - 3:26many of these cumbersome creatures
pass their time grazing the seabed. -
3:26 - 3:29Sea cucumbers are found everywhere
from shallow shores -
3:29 - 3:33to abyssal trenches 6,000 meters
below sea level. -
3:33 - 3:38On the deep sea floor, they comprise
the majority of animal biomass, -
3:38 - 3:42reaching up to 95% in some areas.
-
3:42 - 3:46As these sausage-shaped wonders
trudge along, they vacuum up sand, -
3:46 - 3:50digest the organic matter it contains,
and excrete the byproduct. -
3:50 - 3:55In this process, sea cucumbers clean
and oxygenate the seafloor -
3:55 - 3:58by breaking down detritus
and recycling nutrients. -
3:58 - 4:03This creates the conditions for sea grass
beds and shellfish to thrive. -
4:03 - 4:07Sea cucumber excretions can also aid
in coral formation -
4:07 - 4:12and may play a role in buffering marine
environments from ocean acidification. -
4:12 - 4:15As the ocean’s vacuum cleaners,
they are very good at their job: -
4:15 - 4:17about half of the sandy seafloor
-
4:17 - 4:21is thought to have passed through
the digestive tract of a sea cucumber. -
4:21 - 4:25So next time you’re rejoicing
in the feeling of sand -
4:25 - 4:28crunching between your toes,
consider this: -
4:28 - 4:32those very grains of sand might have,
at one point or another, -
4:32 - 4:36been excreted by a pickle
that breathes through its butt.
- Title:
- This sea creature breathes through its butt - Cella Wright
- Speaker:
- Cella Wright
- Description:
-
View full lesson: https://ed.ted.com/lessons/the-most-important-anus-in-the-ocean-cella-wright
Is it a fuzzy sock? An overripe banana? A moldy tube of toothpaste? In fact, it’s a humble sea cucumber: a brainless, fleshy form surrounding a digestive tract, and bookended by a mouth and an anus. And while it might look odd, its daily toil paves the way for entire ecosystems to thrive. Cella Wright journeys to the bottom of the ocean to explore the lives of these sausage-shaped wonders.
Lesson by Cella Wright, directed by Guto BR, Flávia Godoy and Lívia Serri Francoio.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 04:41
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lauren mcalpine edited English subtitles for This sea creature breathes through its butt | ||
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Tara Ahmadinejad edited English subtitles for This sea creature breathes through its butt | ||
Tara Ahmadinejad edited English subtitles for This sea creature breathes through its butt |