Hidden Hermit Crab Anatomy and a pleasnat swim at Kahalu'u

   This morning we got organized bright and early.  Before 9:30 we were parked on the street above the entrance to Kahalu'u Beach Park.  This is the time of the new normal, so right in front of our car was a pair of kapunas, which is Hawaiian for respected elders, washing of their aged white bodies

Cantigaster  jacator, the Hawaiian Spotted Toby.  Kahalu'u   April 2020

after a dip in the bay. A  jug of water brought from home was beside their open trunk.  We greeted each other and I began my trek down to the park.  

   Down at the park, a young couple completed a recreational swim just as I was entering, so once again I had the bay to myself.  The water was pleasantly cool and fairly clear.  The surf is still up but the current was surprisingly moderate.  God had turned off the infinity pool for this swim.

    Early on I nabbed a picture of a Canthigaster jacator.  This was a small fish that was harboring in a coral fenestration.  I set the camera to take his picture in the deep shade, but then he swam out into the open.  I took his picture with the flash as he sat partially exposed behind a piece of rubble.  I think it turned out rather nice. 

The Cone Shell Hermit Crab  Kahalu'u 2020

   Heading towards the breakwater, I looked in another cavity to see a large cone shell.  At first I thought the ball of this rounded cone, possibly a flea cone, was a s big as a golf ball.  As  I swam away I reduced it to as big as a ping pong ball.  In fact, it was probably the size of a large grape.  Anyway, as I watched, a large cone shell hermit crab emerged from the cone shell.  This time the object of my desire was going to stay in the cavity and I used the flash to get the picture you see here.

   John Hoover says that this crab is usually found below 20 feet.  It is common in the shallows here and elsewhere on the Kona coast.

   It was a cool breezy day and as I swam towards the middle of the bay the wind whistled around the top of my snorkel.  Soon I happened upon a truly superior hand hold.  Fashioned from dying coral and looking like the grab bar on the back of a seat on the metro, it was too good to pass up.  I hung on, facing into the current and got a picture of a small arc eye hawkfish.  All I had to do was hold steady, point and shoot.  Isn't that an amazing picture?  Good camera.

    About 40 degrees to the right of the perch now vacated by the hawkfish and only a couple feet away I spotted a small shell sitting in an exposed coral depression.  If you are an avid reader of the blog, you know that such shells belong to snails who make their living in the sand.  When you see one sitting on top of a coral it can only mean one thing...Hermit Crab City!  Like the long arm of the law, I reached out and plucked the shell, placing it in a handy depression a half foot away.

A Hidden Hermit Crab in a Pimpled Basket  Kahalu'u 2020

   You will notice that this is an elongated shell.  The uninitiated might think that this would make the shell easy to identify.  Well, au contraire, mes amis.  As it turns out, there are any number of elongated shells.  There are triphorids, obelisks, wentletraps and whelks...spindles, doves, false tritons and miters. And there are baskets. To the best of my ability as a sea shell taxonomist this is a pimpled basket.  Sort of reminds you of some high school student taking the metro to basketball practice somewhere in the Bronx.  One should suspect that the shell is a basket if the aperture is small and round...basket-like.

   If memory serves, back in the day when we kept hermits in an aquarium on the lanai at Alii Villas, we had among our collection of shells a pimpled basket and a punctured miter.  At first glimpse these elongated shells might be confused; The aperture on the miter is elongated so it would make a lousy basket.  At night, the hermit crabs would fight and, in the process, exchange shells.  We could here them clacking through the night.  A great part of the fun was checking on the tank in the morning to see which hermit was in which shell.  If you have any questions about this, look at the Hermit Crab Patch.  Sandra and I are not the only ones to catch hermit crab mania, which is a hell of a lot safer than catching covid 19!

https://www.hermitcrabpatch.com/Hermit-Crab-Anatomy-a/136.htm

    Anyway, back at Kahalu'u the hermit crab emerged in short order.  I started snapping away and made off with these two pictures presented here.  The one with the crab emerging shows off the basket shell with its tidy round aperture to good advantage.  The second gives you a delightful look at this hermit crab.  Those lovely blue ankle patches with  the delicate purple streaks confirms that this is a Hidden Hermit Crab, Ca. latens.   This is not an uncommon species at Kahalu'u. 

   In both pictures you can see the long yellow antennae waving gaily on each side of the face. These are,in fact, called antennae and the the nice people at the Hermit Crab Patch tell us they are primarily used as feelers.  But look in the middle, between those

Note the atennules between the eye stalks!

beige eye stalks.  The second picture shows a matched pair of structures: tiny blue tubes from which project the most delicate orange strands. These are attennules, a second set of antenna-like structures that are associated with taste and smell.  Prior to today, I wasn't aware of these structures and I certainly didn't know how beautiful they were,  however small. It is the atennules that alert the hermit crab to food when you feed it in your aquarium.

   After my close encounter with the hermit crab, I followed a pair of lined butterflyfish around the bay and then crawled through the exit, it being dead low tide.    As I was taking my shower, two other couples arrived and negotiated the shallow entry.  Its really nice to be back in our bay.  

jeff

Kahalu'u is open.And you can have it all to yourself.  Photo SKG.