Tag Archives: Crabs

Seven-eleven crab

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A Seven-eleven crab off Hawaii

I’ve only seen one or two seven-eleven crabs (Carpilius maculatus) before, and not for several years. My wife had never seen one. One reason for this is that the crabs are active at night. But we saw this one a few days ago, scuttling over the rocks and sand. It was quite early in the morning, so the crab was probably headed for its home.

These crabs are quite large and have the distinctive markings that give it its name. There are the two spots alongside each eye and three across the center of the shell. Four more spots are less obvious on the back edge of the shell.

In Hawaii, these crabs are called ‘alakuma. Legend has it that a god caught an ‘alakuma, but the crab struck back and drew blood. This happened a second time, before the god finally snagged the crab. But the crab’s descendants continue to bear the markings of the god’s bloody fingerprints.

Pallid ghost crab

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A Pallid ghost crab on a beach in Hawaii
A Pallid ghost crab on a beach in Hawaii

I saw this crab on the beach south of Kohanaiki Park. Pallid ghost crabs are small, with a carapace only an inch or so wide. They’re also speed demons, zipping across the sand, usually to disappear into their holes. That’s how I saw this one, on the move. But instead of diving for cover, it remained above ground.

I took some photos from distance before edging closer to try and capture more detail. The crab didn’t move. My biggest challenge was finding it in the camera’s viewfinder. Even though I knew where it was, half the time I wasn’t sure whether I had it in shot or not, they blend in so well.

The top photo shows the best of the close-ups. The second one gives an idea of the crab’s perfect coloration for its environment.

Stick swimming crab

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A stick swimming crab in the waters off the Big Island, Hawaii

This month, Becky’s April Squares challenge theme is ‘Bright.’ (See more responses here.) First up I thought I’d share something very unusual, which I consider myself lucky to have seen.

You’ve probably heard of stick insects, but the stick swimming crab is a far less often encountered creature. Most crabs scuttle about on the sea floor, but swimming crabs have flattened segments on their legs, which they use to propel them through the water. But even with this different method of propulsion, swimming crabs tend to stay close to the bottom.

The stick swimming crab (Charybdis baculum) has a different approach. It heads for the bright light at the surface where it paddles along, maneuvering with its spindly legs. It will sometimes snag bits of floating debris and attach them to its body to enhance its appearance. Its goal is to look like a small, drifting haven for juvenile fishes and other marine organisms that often gather under such floating islands, which offer them some protection from predators. With the stick swimming crab, that safety is an illusion. Instead, they’re part of the crab’s lunch box, to be picked off at its leisure.

Stick swimming crabs spend most of their time at the surface, but return to the sea floor for periodic molts. This one looks like it has recently molted.

Oh wait, it’s just a stick.

Also posted in response to this week’s Friendly Friday challenge theme of “Something Learned.” See more responses here.

Wandering along with a wandering tattler

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When I was down at Kiholo recently, I saw this wandering tattler at the shoreline, hunting around for a bite to eat. I followed it for a while, from a distance.

It snagged a katydid at one point (second photo), but I didn’t see it catch anything else. It spent a fair amount of time around one particular rock (third photo), which caused a good deal of consternation for the a’ama crab that was there. I think the crab was a bit too big to fall into the category of prey for this particular bird.

Jeweled anemone crab

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My wife spotted this crab scuttling quite rapidly along the floor of the bay where we were snorkeling. It was clearly some kind of hermit crab, but it was quite deep and this was the best photo I got.

When we got home, I looked through my copy of John P. Hoover’s Hawaii Sea Creatures and the jeweled anemone crab seemed the most likely identity. As can be seen in the photo, the shell is covered with anemones which is a feature of these crabs. Since these crabs are mostly night feeders, we were lucky to see one still active in the early morning. Possibly it had been disturbed and was headed to a new hiding place.