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.
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.
This is the molted shell of an a’ama crab, seen on the North Kohala shore. A’ama crabs are numerous around the Big Island and they scuttle away when disturbed. But while these crabs are black, their molted shells turn red in the sun, as this one has.
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.
It’s not unusual to see green turtles hauled out on shore. Sandy beaches are prime resting spots, but these three chose this rocky bay, only a few hundred yards from some of the best beaches on the island. Perhaps they valued quiet over easy access.
The middle one of the three had gained a passenger that I didn’t notice until I processed the photos, an a’ama crab, making the most of its excellent vantage point.