Rain Posture in Yellow Garden Spider

Earlier this summer, I was able to observe a yellow garden spider (Argiope aurantia) that built its web next to my parents’ front door. I noticed that it displayed a peculiar behavior in each of several heavy rainstorms. Instead of fleeing its web when the big raindrops started to pour down, the spider stayed near the center of its web. It let go of the web with its front legs, but continue to hold with its hind legs. This peculiar behavior resulted in the spider hanging perpendicular to the ground. I watched the spider do this through several heavy rainstorms, so it wasn’t just a one-time fluke. Such a distinct behavior may be an adaptation to deal with the rain. For example, perhaps this behavior reduces the amount of the spider’s body vulnerable to hits from raindrops. If it reduces hits from raindrops, the spider may be less likely to be injured or knocked from its web.

Here is a photo of the spider in its normal posture, when there is no rain:

Yellow garden spider after the rain

And here is a photo of the spider in a heavy rain, with its body oriented perpendicular to the ground.

Rain posture in yellow garden spider

Here is a video of the behavior:

I also wondered if this behavior had been observed in other spiders. After searching a bit, I found that two spider biologists, Robinson and Robinson, had described this behavior in a 1974 paper on Giant Wood Spiders in New Guinea:

From our observations on Argiope argentata in Panama, we know that some spiders may adopt special rainfall postures if they remain in their webs and do not seek shelter under nearby vegetation. Thus Argiope argentata hangs away from its sloping web so that the body is almost perpendicular and legs I and II, which are always directed anteriorly, are off the web. In the rainfall posture these two pairs of legs are held outstretched in line with the midlateral plane of the body and at a fairly acute angel to the long axis, i.e., they are held more anteriorly than in the normal resting attitude. This position could be interpreted as minimizing the cross-sectional area exposed to the rain – assuming that tropical rains fall more-or-less vertically – or that the spider in this position maximizes the flow of water off its body surface with the anterior appendages forming a sort of drip-tip. We have since seen this behavior in Nephilia clavipes, and Leucauge species.

To wrap this post up, here is a final photo of the spider eating (note that the spider only has seven legs):

Argiope aurantia eating prey

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Shed Snake Skin Identification

I was recently given some shed snake skins that were found at the CWRU Farm in northeast Ohio. These sheds will provide a fun way to teach CWRU herpetology students snake identification skills. Shed snake skins have a number of characters that can be used to identify the species of snake.

This shed was large, which allowed me to rule out some of our smaller northeast Ohio snakes, like the Ringneck Snake and the Red Bellied Snake.

Shed Milksnake Skin

Shed Milksnake Skin

I looked closely at the scales to determine whether they were keeled or smooth. Keeled scales have a small ridge running down the middle, whereas smooth scales lack the ridge. By examining this close-up view of the scales in the photo of this shed, you can see that they are smooth. Since this shed has smooth scales, we can rule out several additional species, including the Northern Water Snake and the Garter Snake. We can also rule out the Black Rat Snake, as it has weakly keeled scales.

Shed Milksnake Skin

This leaves a couple snake species that could be the source of the shed: Eastern Milk Snakes and the Black and Blue Racers (which are geographic variants of the same species). To separate the remaining snakes, we need to look at the anal plate. The anal plate is the last of the large belly scales on the snake’s body, and it is located directly over the snake’s cloaca (excretory and reproductive orifice). The photo below shows the anal plate (circled). In this photo, the snake’s head would be to the right, and the tail would be to the left.

Shed with Anal Plate Highlighted

As you can see from the photo, the anal plate on the shed is single, not divided. Racer snakes have divided anal plates, but Eastern Milk Snakes have single anal plates. So this snake ends up as an Eastern Milk Snake (Lampropeltis triangulum):
Eastern Milk Snake

Interested in using scale traits to identify snakes? You can find all the information you need in the Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America or the Field Guide to Western Reptiles and Amphibians.

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Brood V Cicada from Warrensville Heights, Ohio

Here is one of two Brood V Cicadas that I spotted in a parking lot in Warrensville Heights, Ohio, on 19 June 2016. I’ve also recorded this observation in inaturalist. This is the first time I’ve seen these cicadas in my life, so it was pretty exciting!

Brood V Cicada

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Difference a day makes: Bullfrog Egg Development

Adult Bullfrogs are the largest North American frog, and even their tadpoles can be a handful. But they start their lives at a much smaller size. Here are two photos showing one day’s development of a bullfrog egg. The first photo shows a bullfrog egg about one day after it was laid, and the second photo shows a bullfrog egg about two days after it was laid.

Bullfrog egg:  1 day old

Bullfrog egg:  2 days old

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sucking the blood of frogs

A couple years ago I posted about leeches eating frog eggs. This year I spotted a struggling juvenile green frog floating near the surface of a pond. It was partway through metamorphosis, with all four legs, but also a long tail. As it slowly rotated in the water, I realized a large leech was attached to its side. I suspect that the green frog may have ultimately been killed by the leech.

Leech attacks metamorphosing green frog

On the same day, I spotted this big male green frog. There are variety of ways to tell a frog’s sex, such as looking at throat color, or for the presence of nuptial pads. In the case of green frogs, mature males are identified by the large size of their tympanum. And right above this male’s tympanum is perched a hungry mosquito.

Male Greenfrog w/ Mosquito

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