Why would an underwater creature remain lodged to its prey?

Question

Enter the [Insert cool and awesome Latin name here] - this species is 3 times the size of a lobster from front to tail, and a powerful hunter. Operating in swarms, they are my worlds equivalent of the piranha, except they don't really have any predators.

It has an armored shell, with shell-dorsal fins to stabilze its fast forward movement and a powerful, whale-like tail to give it forward thrust. The tentacles on the sides and front allow it to maneuver; by using them to spin, it can rotate and turn, similar to how a plane would roll to perform a turn. Not depicted properly is that the forward tentacles actually are sharp and tough, and can be used as weapons if required.

The Gills are on the bottom of the creature, similar to the manta ray, and the mouth operates like a crabs mouth.

However, the main issue I have run into is with its method of hunting. I want these creatures to dart forwards and ram into its prey, lodging itself into the subject before using its mouth and forward tentacles to rip it apart.

(Please forgive the poorly sculpted, unrealistic barbs)

But I see a problem with this hunting model. I can't figure out a logical, proper reason (other than them lodging themselves into the sides of their prey to feed) that being attached to their prey would be more effective than simply having a barb-less horn, allowing the prey to bleed out by pulling out the horn, which also allows more stabs and more holes.

Shrimp, which have barbed horns, don't seem to use them to hunt (or rather, I can't find any reference to them doing so, and have only vaguely seen mention of the horn being able to be used for "attack and defense").

Swordfish don't have barbs, but they definitely don't stab - they slash instead.

While Dolphins ram using their tough noses, they don't penetrate to cause damage.

Even humans have designed ships which sometimes have naval rams, but while they did penetrate other ships, they weren't designed to stay lodged in the enemy ship.

Piranhas take bites out of their prey, they obviously don't stay lodged on them.

So the question is: What would cause an underwater hunting species to evolve a barbed horn, such that the purpose of said barbs is to remain lodged into the prey?

Some additional information that may be (but most likely isn't) useful:

• This creature can reach speeds of up to 90km/h
• The creature can use echolocation
• The tail, underside, and tentacles of the creature has a dolphin-like "skin"
• The black dots on the front of the shell are eyes
• All tentacles are able to retreat into the shell, similar to how the head of a turtle can be pulled all the way into the shell
• The shell is very tough, and the horn especially dense. For the purposes of answering this question, you may assume that the horn will not break off.
• This creature can hunt both in shallow and deep water.

Answer 1

To be annoyingly clingy

Your super lobsters seems to have the ability to hunt anything. The barbs makes it easier for a team of them to hunt prey much larger than themselves. The main purpose of barbs is, as you state, to remain attached to whatever you are trying to kill. When hunting in a team after large prey, the first of the lobsters to ram it, and just keep attached to slow it down for the others to reach it. Others then do the same, and keep attaching more and more lobsters to the poor victim in a very painful but inescapable process.

The usual defence for a big creature against smaller predators is to sling them away, and literally "get them off your back". If you can not make them lose their grip, you have a big problem. The super lobsters can just hang on and continue their strategy, in something that is surprisingly similar to a DoS attack, eventually breaking down the capacity of the target.

Answer 2

Because you are a sprinter only (in contrast to your prey)

Some animals such as cheetahs are not capable of hunting a prey such as a gazelle for more than a few hundred metres. The gazelle is capable of long distance running. So their tactic is super high speed (fast land animal on earth) on super short distance, knocking down their target.

Obviously in water you can not knock down someone - but as one strategy, you may concider attaching yourself to the target, and gradually kill your prey.

Which matches your description!

So an answer could be: attaching yourself to the target is the only viable way in water if you are a sprinter and can not kill instantaneously!

Killing could be by venom, or the effects of the damage caused by the barb. Or both. Perhaps, your prey is simply orders of magnitude larger (think whale), so that effects take time. In either case, if instead the prey would get away, or die further on due to damage received, it would fall prey to some other predator, and the super lobster would receive nothing.

Answer 3

They feed through their horn

There are animals that already do this, the most famous of which are leeches, ticks and lampreys. They attack their prey, latch on, feed, then let go once they're either full or in danger.

Answer 4

Co-evolution.

Think about the evolutionary context like this.

10 million years ago, an ancestor of [Insert cool and awesome Latin name here] (Icaalnh) would mostly kill its prey with ease using its sleek spike.

The 'ones that got away' had denser fat deposits/thicker skin/swam faster than the primordial Icaalnh - and due to natural selection, these became the dominant forms - fatter and faster, less likely to bleed to death - and even if they did, would be likely eaten by other predators.

Random mutations in spike growth lead the Icaalnh to in-turn evolve the barbed spike as part of the ongoing evolutionary arms race.

Answer 5

It could feed as a parasite, always attached to its host, like a lamprey, or the exceedingly creepy Cymothoa exigua, which replaces a fishes' tongue.

Answer 6

Sounds like the super lobster is a fast predator (90kmph!) which means the prey is just as fast too. Its teeth and claws from the diagram would not be strong enough to catch and kill or incapacitate fast prey of equal or bigger size quickly enough before the prey got away if the super-lobster were to just bite or scratch. Especially if the prey has thick skin or is armoured.

The barbs could have venom or digestive enzymes that act to either dissolve flesh spider-style. Maybe it's a leech-like creature that drinks blood, eats flesh and lets go when it's full. Maybe it evolves in a world of armour plated prey and needs the extra time to bore through the armour and deliver the killing blow.

Lions and tigers do latch onto prey such as buffalo while hunting to weigh them down and allow access to the jugular vein. Crocodiles too latch on and wait till the victim dies of bleeding or drowning. Super lobsters are not so illogical.

Cool btw, those diagrams look great!

Answer 7

It hunts whales. Like a tic, it would embed it self and continue feeding on it's host. If the host is large enough it's conceivable it could live a long time with the crab-tic attached. Or maybe once it digs in, the crab-tic could live in or just under the host's skin, not necessarily eating but more parasitical. Or ever symbiotic. Just don't let it attach to you head for a half life.

Answer 8

They might not feed instantly. If they didn't stay out long from hunting, it may be a valuable to be able to stab once and then be able to swim back to their nest (or whatever it's called) and eat there as opposed to a fight first.

Answer 9

1. A solitary hunter, the uberlobster could latch onto a fish with its horn, paralyze it with a crippling neurotoxin that it excretes from its body, and eat the fish alive as they fall to the sea floor. While the most brutal method in the list, it is not particularly effective against social animals, as other members of the school could simply pull it off the helpless fish or gang up on the uberlobster while it feeds. The barbed horn doesn't seem particularly easy to pull out, both for the lobster or the fish. Larger, solitary prey animals with coarse skin would be ideal to latch upon.

2. Patient and cunning, the uberlobster simply plucks a little fish from its school near the surface, impales it upon its horn, and swim towards the deep sea, waiting for it to die. The barbs would keep the fish from escaping. As the fish has not adapted to its new environment, it will implode on itself. Somewhat time-consuming, though its incredible speed would easily quicken the process, but effective on the schools of fish mentioned above. For obvious reasons, this tactic wouldn't work on larger prey animals, as the uberlobster would not be able to drag it down.

3. Simply put, the uberlobsters are the communists of the sea. While one pack member slows down and distracts the prey, the rest of the uberlobsters move in and go for the kill. They might either share the prey with each other or fight for the largest share. As other answers have eloquently shown, animals with strong, showy, and intimidating claws, crabs in particular, primarily use these to "settle disputes" with other members of their species.

Answer 10

In the animal kingdom, articles that often look like they have evolved for hunting are actually never used as such. In these cases they may be for territorial spats or fighting off rivals to protect or acquire a mate or mates. Sometimes these articles are less deadly than the primary hunting equipment of the animal so as not to snuff out a potential relative who carries similar genetics, or a potential source of genetically diverse offspring for their own future offspring to mate with.

Even if this your creature does not use its gnarled horn in this way, it could be a vestigial horn used this way by distant ancestors.

Answer 11

Poison!

Bee's sting you and leave their butt-sack attached, so that the poison can keep pumping into you. I don't know why the bees do this, because it seems they mostly die after this (so why not stay around?)

Anyhow, super-lobster-Mk-VII injects poison through its horn, it would be able to take down very large prey if it stuck around long enough for lots of poison to go in through the puncture.

Answer 12

Enter the Eunice aphroditois or Bobbit worm.

This underwater invertebrate hides under the sand, waits for prey to swim over them and then shoots up and grabs the prey with their massive jaws. They then drag it underwater and slowly devours it.

Now while this 10 foot long monster worm is very different from [Insert cool and awesome Latin name here] (Maybe Gurgustium Venator Latin for Barbed Hunter) the principle is still the same. Have your species rely on hunted by grabbing and dragging their prey.

Answer 13

Cnidaria : Cnidocytes. These cnidocytes are activated in 10 ms, the deployment is considered rapid. This is a venom delivery system, however, its ability to secure objects is fairly prominent.

From wiki:

Penetrant: The penetrant or stenotele is the largest and most complex nematocyst. When discharged, it pierces the skin or chitinous exoskeleton of the prey and injects the poisonous fluid, hypotoxin, that either paralyzes the victim or kills it.

Glutinant: a sticky surface used to stick to prey, referred to as ptychocysts and found on burrowing (tube) anemones, which help create the tube in which the animal lives

Volvent: The volvent or desmoneme is a small and pear-shaped nematocyst. It contains a short, thick, spineless, smooth and elastic thread tube forming a single loop and closed at the far end. When discharged, it tightly coils around the prey. They are the smallest nematocysts. A lasso-like string that is fired at prey and wraps around a cellular projection on the prey, referred to as spirocysts

Specialized types can be used to stick or to envenom, it should fit your latching requirement if there are enough.

Answer 14

These sort of parasites hang on to every mammal in the sea and on land. They feed off the host and hang out, sucking its blood while it does all the work wandering and flapping and navigating while the parasite tags along for free. The parasite either injects eggs or drops off to do its own reproduction stuff.

Maybe another idea, but very dark. Mammals such as dogs groom ticks all the time if they can reach them. So the ears and eyelids are favorite targets, as unless the dog has a grooming friend, the parasite won't be nibbled off, since the dog can't articulate to reach them. Alternatively, it could stick its fangs into the genitalia of the creature and hang there, while the owner is too afraid to do anything about it for fear of pain or losing his own reproductive potential.