Arizona Fishing Spider
(One Bad Ass Spider)
November 15, 2013
By Matt Marine
First, I am not an Entomologist, nor am I an Entenmannologist (which are the study of insects and great tasting breakfast pastries, respectively). I believe the above spider is a fishing spider, thanks to information provided by subscriber Brian S., but don't quote me on it.
Second, I do know that IF the above spider is a fishing spider, they are a bad ass spider. I wouldn't want to be shrunk down to their size and go up against one of these bad boys (or girls).
Thirdly, I found these spiders during our trip to Pena Blanca Canyon on a rainy Labor Day in 2013. The canyon was full of water and the surrounding vegetation was thick and green. I felt as though I was touring South America and not the Sonoran Desert that day. Seeing these huge spiders was just the icing on the cake.
Fishing spiders are known by many different names: raft spiders, dock spiders and wharf spiders. What's common with all these names is they have something to do with water, which may seem unusual for a spider.
But these spiders have adapted to life around and on top of water. They live near small lakes, ponds and quiet streams where they hunt a wide variety of prey - including fish!
There are over 100 known species of fishing spiders. They come in a wide variety of sizes and colors, with many having a pale stripe down the length of their body. It isn't too uncommon to come across females that are over three inches long (which I would put the size of the ones we saw on our trip). This often leads to a common mistake to label these spiders as wolf spiders.
Water and the Spider
The fishing spider is at home on top of or below the water. First, they are covered with very short hairs which are unwettable. These allow them to stand and walk on top of water much like pond skaters. You can see from my photo below the surface tension created by these hairs on the water allowing the spider to "float" on it.
They can also "breath" under water. When they submerge, a fine film of air becomes trapped in these hairs. They breath this trapped air while under water. This coat of air often gives them an appearance of polished silver or liquid mercury while under water.
But it comes at a cost. All of this air makes them very buoyant and they can only stay submerged for short periods of time unless they hold onto something. When they let go, they pop to the surface like a bobber.
Awesome Aquatic Predators
Fishing spiders are magnificent aquatic predators. Their diet include a wide variety of insects, aquatic bugs and even small fish and frogs. They use the surface of the water much like a traditional spider uses a web. The spider waits on water, using their legs to sense tiny vibrations on the surface or below the water. Since these spiders typically hunt at night, their eight eyes play only a secondary role to their sense of touch.
If the prey is on top of the water they will either pounce on it or run on top of the water to capture it. But it's when the prey is below the water that things get interesting. The spider has a few different options. One, it can hold onto something with its rear legs and snatch their prey from above. Two, it can dive down a few inches to reach it. Or three, it can lie in wait under water by holding onto a rock or aquatic plant.
What fascinates me most about these spiders is that they will catch and eat small fish, tadpoles and frogs. And by small, I mean fish and frogs larger than themselves. See the video below (at about the 1 minute mark, you can see one catch a fish). Pretty bad ass if you ask me.
Below is a short National Geographic video that shows a fishing spider eating a frog it had caught that was much larger than itself.
Male vs. Female (Otherwise Known as Breeding)
The female fishing spider is typically larger than the male and that's unfortunate for the male spider. Here's a passage on the fishing spider I found particularly interesting from Wikipedia, "If a female chooses to eat a male after mating, there is usually little he can do about it. This behavior may help the female by providing the nutrition she needs to produce healthy young, while the male gets the benefit of passing his genes on to a well-fed next generation." Wow! I bet the person who wrote that passage is a "glass half full" person. Remind me never to pick up a female fishing spider at a bar.
Who Preys on Fishing Spiders?
As with most spiders, typical predators include birds, snakes, other larger insects and because they spend time on/near the water, fish and frogs (I guess this is to return the favor from above). Another predator is a parasitic wasp as stated in the same Wikipdedia article. It "... stings the spider to paralyze it before carrying it off and laying an egg in its abdomen. The larvae of the wasp hatch and proceed to eat the spider from the inside out. One escape technique the spiders use is to disappear beneath the surface tension of the water. However some wasps counter the disappearing trick by going into the water to sting the spider and drag them out of the water."
Sounds a little like the movie Alien again (remember the Horsehair Worm?). Next time I have a bad day at work, I need to remember I don't have live larvae eating me inside out!