I am imagining a race of spider-like creatures that remain still in the water. They glow to attract prey/would be predators. They surround themselves with a thick layer of slime that can catch creatures much larger than them. I need my creatures, however to be able to quickly get through their own cloud of slime. It has to be able to restrain a shark and they have to be no larger than a cat.

They kill their prey with venom injection via biting.

How can my creature evolve to meet these criteria? What is this slime made of? How can my spider get through it?


The multiple types of spiders exist at various depths, although I am trying to figure out how the deep sea ones would work.

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    $\begingroup$ The hagfish produces slime. You might find a starting point there. $\endgroup$ – Frostfyre May 26 '15 at 16:35

The hagfish, not actually a fish, but an invertebrate, (http://en.wikipedia.org/wiki/Hagfish) exudes a substance that is made up of cloud of microfibers that causes the water to thicken around it, trapping predators while the hagfish itself wiggles free by tying itself in knots. A spider wouldn't want to exact same thing, but it could use a similar trick, a web made of fibers that when contacted expand and thicken with the water, causing the prey to thrash and contact more strands of the web eventually holding it perfectly still. If you wanted to make it extra creepy and unique, it wouldn't even have to use a toxin to kill, the webs thickening agent could clog the gills of the prey like the hagfish as well.

As far as moving through the web, most spider webs are built of two different kinds of fibers, some sticky and others not. The spider knows which ones it can safely step on since it made the web, but everything else is totally clueless.

The spider could also exude a substance onto it's carapace that effectively dissolves the fiber that touch it, letting it move uninhibited through thickened web sections to bite prey and inject their toxins that liquefy the insides and make it easy to feed.

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    $\begingroup$ Thanks for the answer. For future answers can you divide into multiple paragraphs for readability? $\endgroup$ – JDSweetBeat May 26 '15 at 17:40

That would be a fairly large spider, but if it lives primarily under water then it's a bit more feasible.

It's probably easiest if it evolved from existing water dwelling spiders.

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These spiders bring bubbles of air down for them to breathe. These bubbles may actually act as a shiny lure for fish and larger ocean predators. This means bioluminescence is not required.

If the spider can craft large enough bubbles it may only need its prey to accidentally breach the bubble, the spider could then rapidly seal the breach and the gilled creature would suffocate and become weakened inside the gas atmosphere of the bubble. Allowing the spider to easily finish it off.

Alternatively the spider would simply create a web network which has gaps large enough for it to pass through while a larger creature will get tangled if it tries to follow. Once trapped, the spider can finish off the prey and drag it into its bubble for consumption.

The web, if woven in a mesh, would appear to be slime to the uninitiated. It would have a much higher tensile strength than slime though.

Another sort of out there option is for the spider to actually tend to a small farm of sessile nematocyst-wielding creatures, cnidarians. Weaving a structure for the cnidarians to live on, the cnidarians would sting and paralyse any large creatures who wandered into the web. The spider could then capture the prey and give its corpse back to the cnidarians to feed them and keep things clean. This would be similar to some small crabs who live in sea anemones.

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    $\begingroup$ Thanks for the nightmares. I didn't want to sleep tonight anyway. $\endgroup$ – corsiKa May 26 '15 at 22:15
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    $\begingroup$ @corsiKa Unless you sleep in the ocean, you should be safe. Well, except from the teleporting spiders. They are more than likely to get you. The worst part is their teleporting sounds exactly like a building creaking and settling at night. $\endgroup$ – Samuel May 26 '15 at 23:57

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