| PARASITIC CRUSTACEANS |
| Ommatokoita elongata |
While never known to attack humans, the Greenland shark has been observed snatching
whole reindeer, horses and caribou off the water's edge. It's a powerful predator approaching
the size of the Great White, but a sluggish swimmer that prefers to hang around while the food
comes to it. How it catches such fast-moving prey as small fish and squid has been
somewhat debated, but it has been hypothesized that these animals are attracted to the
shark by a most unlikely lure: a pale, worm-shaped parasite that dangles from its eyeballs.
This squishy, degenerate crustacean feeds exclusively on the Greenland shark's vitreous jelly,
anchoring its mouth parts deep in the host's corneal tissue. Though the fish is nearly blinded,
it can hunt just as effectively by its other keen senses, and prey may see the ghost-white,
enticing "worms" long before they notice the dark, gaping jaws.
Whether this cooperative function is fact or fiction, it's hard not to get a certain sense of
audacity from this bold little sea-louse that has gone to such extreme evolutionary lengths just
to poke a shark's eye out.
whole reindeer, horses and caribou off the water's edge. It's a powerful predator approaching
the size of the Great White, but a sluggish swimmer that prefers to hang around while the food
comes to it. How it catches such fast-moving prey as small fish and squid has been
somewhat debated, but it has been hypothesized that these animals are attracted to the
shark by a most unlikely lure: a pale, worm-shaped parasite that dangles from its eyeballs.
This squishy, degenerate crustacean feeds exclusively on the Greenland shark's vitreous jelly,
anchoring its mouth parts deep in the host's corneal tissue. Though the fish is nearly blinded,
it can hunt just as effectively by its other keen senses, and prey may see the ghost-white,
enticing "worms" long before they notice the dark, gaping jaws.
Whether this cooperative function is fact or fiction, it's hard not to get a certain sense of
audacity from this bold little sea-louse that has gone to such extreme evolutionary lengths just
to poke a shark's eye out.
Virtually every group of invertebrates has its parasitic representatives, and the Crustacea -
the crabs, lobsters and shrimp - are no exception. Primarily found in the ocean, Crustaceans
include some of the most unique and alien parasites of them all.
the crabs, lobsters and shrimp - are no exception. Primarily found in the ocean, Crustaceans
include some of the most unique and alien parasites of them all.
| Photo credits unknown unless otherwise noted. Please e-mail me if you own these images. |
Speaking of tongues, this amazing creepy-crawler (with adorable koala-bear eyes. Look at
those!) really does chow down on them (sort of) and happens to be the only known parasite
that effectively replaces one of the host's body parts. It makes its home exclusively within
the mouth of a fish (usually red snapper), where it feeds on blood until the victim's tongue
withers and dies. Fortunately, the parasite is anchored to the fish's muscles in such a manner
that the host can manipulate the crustacean as a functional new tongue, ensuring that its new
home can continue feeding normally. It has to eat for two, after all.
Stupid site trivia: back in 2002, bogleech.com was the first website to host an image of this animal (top right,
scanned from a textbook) and its name yielded barely one page of google results. Today, there's a wealth of images
and articles available, and you can even read about this guy on cracked.com
those!) really does chow down on them (sort of) and happens to be the only known parasite
that effectively replaces one of the host's body parts. It makes its home exclusively within
the mouth of a fish (usually red snapper), where it feeds on blood until the victim's tongue
withers and dies. Fortunately, the parasite is anchored to the fish's muscles in such a manner
that the host can manipulate the crustacean as a functional new tongue, ensuring that its new
home can continue feeding normally. It has to eat for two, after all.
Stupid site trivia: back in 2002, bogleech.com was the first website to host an image of this animal (top right,
scanned from a textbook) and its name yielded barely one page of google results. Today, there's a wealth of images
and articles available, and you can even read about this guy on cracked.com
Named not for tongue-eating but for a the tongue-like appearance of certain species, the
"Pentastomida" are creatures with such minimal anatomy that they were only thought to be
Crustaceans by the 1970's. This confusion wasn't helped by their strange choice in hosts;
rather than plaguing the bodies of aquatic life, tongue-worms favor the lungs and sinuses of
predatory birds and reptiles.
Pentastomida translates to "five openings," as many species bear a five-pronged, hand-like
head tipped with orifices once mistaken for identical mouths. We now know that the parasites
have only a single mouth and four gripping appendages.
"Pentastomida" are creatures with such minimal anatomy that they were only thought to be
Crustaceans by the 1970's. This confusion wasn't helped by their strange choice in hosts;
rather than plaguing the bodies of aquatic life, tongue-worms favor the lungs and sinuses of
predatory birds and reptiles.
Pentastomida translates to "five openings," as many species bear a five-pronged, hand-like
head tipped with orifices once mistaken for identical mouths. We now know that the parasites
have only a single mouth and four gripping appendages.
Once the larval, female Sacculina locates a suitable victim, it inserts a thin needle into a
seam in the crab's armor, injects a tiny clump of its own cells into the host and discards the
rest of its body entirely, losing more than 90% of its total mass. Now little more than a
protoplasmic blob, it begins to grow through the crab almost exactly like cancer, wrapping
fungus-like tendrils around organs, muscles and even the crab's eyes.
seam in the crab's armor, injects a tiny clump of its own cells into the host and discards the
rest of its body entirely, losing more than 90% of its total mass. Now little more than a
protoplasmic blob, it begins to grow through the crab almost exactly like cancer, wrapping
fungus-like tendrils around organs, muscles and even the crab's eyes.
Soon, the intruder reveals its presence to the outside world as a bulging sac known as the
externa, located where the host crab would normally carry its eggs. If the host happens to be
male, the parasite simply alters its hormonal balance, adjusting the crab's body and
behavior to resemble that of an egg-carrying female.
externa, located where the host crab would normally carry its eggs. If the host happens to be
male, the parasite simply alters its hormonal balance, adjusting the crab's body and
behavior to resemble that of an egg-carrying female.
It is at this point that the male Sacculina finally enters the picture: Injecting itself into the
externa, it fertilizes the parasite's eggs, and the crab is induced to nurture them as it would its
own, carefully cleaning and protecting the bag of baby barnacles. Eventually, the crab will
climb atop a rock or coral and shake its body in the water's current, the same action normally
used to release crab larvae. The crab will spend the rest of its life raising the offspring of this
cancerous invader again and again, unable to ever reproduce with its own kind.
externa, it fertilizes the parasite's eggs, and the crab is induced to nurture them as it would its
own, carefully cleaning and protecting the bag of baby barnacles. Eventually, the crab will
climb atop a rock or coral and shake its body in the water's current, the same action normally
used to release crab larvae. The crab will spend the rest of its life raising the offspring of this
cancerous invader again and again, unable to ever reproduce with its own kind.
| Tongue Worms |
| Cymothoa Exigua |
| Sacculina |
| THAT IS NOT A HAT MR. FISH! |
Argulus are perhaps the most widespread and well-known of these creatures, which cling to
their hosts via a pair of large suckers (modified antennae) and feed on blood or pre-digested
tissues. As you know all too well by now, this is as normal as most parasites come. Other
crusty critters have taken far weirder twists...
their hosts via a pair of large suckers (modified antennae) and feed on blood or pre-digested
tissues. As you know all too well by now, this is as normal as most parasites come. Other
crusty critters have taken far weirder twists...
So...we've seen Crustaceans that attack the eyes, the mouth, the lungs and even the
rectum....where else would you absolutely never want a giant bug to grow? Your brain? Your
genitalia? How about a two-for-one special?
A genus of barnacle, Sacculina begin their lives much like their relatives as a free-swimming
larva or "nauplius" looking for a place to settle down. Unlike their relatives, said place is within
the body of another crustacean, a living crab. There are several species attacking several
different hosts, and in some locations nearly half of a crab population can be infected.
rectum....where else would you absolutely never want a giant bug to grow? Your brain? Your
genitalia? How about a two-for-one special?
A genus of barnacle, Sacculina begin their lives much like their relatives as a free-swimming
larva or "nauplius" looking for a place to settle down. Unlike their relatives, said place is within
the body of another crustacean, a living crab. There are several species attacking several
different hosts, and in some locations nearly half of a crab population can be infected.
The majority of parasitic Crustacea fall under the catch-all term of "fish lice," and usually
belong to the amphipoda or copepoda (water fleas - tiny shrimp-like organisms) while others
are highly specialized isopoda (the same animals as pillbugs and woodlice).
belong to the amphipoda or copepoda (water fleas - tiny shrimp-like organisms) while others
are highly specialized isopoda (the same animals as pillbugs and woodlice).
| Sarcotaces |
And to think all you gamers thought *head* crabs were frightening.
Scarcely resembling a crustacean so much as some bloated, otherworldly maggot,
Sarcotaces is virtually invisible when it swims up the backdoor of its preferred host, the
rockfish. Attaching like a tick to the delicate membranes of the rectum, it begins to gorge on
blood and releases an enzyme that causes the host's own body to grow a protective bag or
"gall" around the intruder. A bag made of anus. Now impossible to dislodge, the parasite
freely grows to around the size of a golf ball, which would be bad enough if the host were our
size, but we're talking about a somewhat smaller fish here. Not only does the parasite make a
sleeping bag out of rectum skin, it grows too large to ever fit back out either way. All the while,
the parasite reproduces and releases its microscopic young, making it not only rude for the
host to break wind at social gatherings, but positively terrifying.
Thank Dryodora for taking one of the internet's first quality photos of an absolutely fascinating beast! It's about damn
time, internet.
Scarcely resembling a crustacean so much as some bloated, otherworldly maggot,
Sarcotaces is virtually invisible when it swims up the backdoor of its preferred host, the
rockfish. Attaching like a tick to the delicate membranes of the rectum, it begins to gorge on
blood and releases an enzyme that causes the host's own body to grow a protective bag or
"gall" around the intruder. A bag made of anus. Now impossible to dislodge, the parasite
freely grows to around the size of a golf ball, which would be bad enough if the host were our
size, but we're talking about a somewhat smaller fish here. Not only does the parasite make a
sleeping bag out of rectum skin, it grows too large to ever fit back out either way. All the while,
the parasite reproduces and releases its microscopic young, making it not only rude for the
host to break wind at social gatherings, but positively terrifying.
Thank Dryodora for taking one of the internet's first quality photos of an absolutely fascinating beast! It's about damn
time, internet.
| Written by Jonathan Wojcik |