Two Great Invertebrates at the Kailua Pier

Christmas Tree Hydra, Kailua Pier 2012

     In this blog I'm going to show you two fantastic invertebrates that I have seem recently, one on each side of the Kailua pier.  One a mollusc and the other something quite a bit further down the evolutionary chain.  I'm assuming here that you are not going to vote for Rick Santorum and, therefore, believe that Chas. Darwin got it more or less right.
    About a week ago, swimming right by the pier, I happened upon a colony of hydras. Hydroids belong to the Phlum Cnidaria, along with jellyfish, sea anemones, and corals.  This may make the phylum seem pretty diverse, but virtually all of these animals exist in two phases, the polyp and the medusa.  A jellyfish is a classic medusa phase, a floating umbrella with suspended stinging organs.  Anemones are classic polyps.  Coral are polyps as well, living inside a stony edifice.  All these polypoid cnidarians have a less well recognized medusa phase.

Pennaria disticha    Kailua Kona Pier

   Hydras are also polyps.  I discovered this colony of Christmas Tree Hydra right next to the pier, very near the colony of sponges we reported on recently.
     As you can see from the pictures, they individual stocks are three to eight inches in length,  projecting branches very much like the frond of some ferns, with the branches alternating off the central stock.   The fuzzy collections on the branches make this hydra look a bit like a white flocked Christmas tree.   The colony is growing on top of the coral and beneath a stone overhang.  This species lives in protected tropical bays around the world.  Like many cnidarians, this hydra is perfectly capable of inflicting a powerful sting.    

Triton's Trumpet  Charonia tritonis  Paul Allen's Reef

     Just today I went for a swim on the Paul Allen's Reef side of the pier.  It was Wednesday, so I was by myself.   Sandra doesn't go into Kailua voluntarily on Wednesday, the day the circus comes to town in the form of the cruise ship.   The circus was in full three ring glory.  The pier was swamped with sea going rats and the representatives of local merchants attempting to attract their business.  The bus from Walmart was there (can you imagine spending your day in Kona at the Walmart?)  and the beach in front of the King Kam Hotel was full of paddle boarders, boogie boarders (no, there isn't any surf what so ever on that beach) and a group that was going snorkeling behind a jet powered sled.  I put on my simple fins and mask and headed out.

Let's hope our Triton doesn't end up like this!

    It had rained the last two days and this always makes the inner harbor colder, as the fresh water percolates into the bay.  Once out past the rip rap the water was warmer and clear.  On the way out, it was me, the usual suspects and the Marian...the glass bottom boat had captured a cargo of sea going rats.  Shortly after I made my turn towards home, with the Marian about fifty yards astern, I spotted a very large sea snail in about twelve feet of water.  A shell this size, I estimated between 16 and 18 inches, could only be a Triton's Trumpet.  I have seen several shells of this species about two to three inches in length serving as the home to large hermit crabs.  You may recall the picture of the Blood Crab in a Triton's Trumpet.  Those shells were the babies.  This is only the second large Triton's trumpet that I have seen in thirty years.  The first was about ten years ago at Honokohau in about twentyfive feet of water.  Unlike this guy, that snail was foraging along the bottom far below.  This snail was attempting to hide for the day, having pulled his operculum, that dish-like plate that you see in the snails aperture, tightly shut.   It must be hard for an animal that large to hide.  One hopes, vainly I'm afraid, that he is safe from collectors.  the Triton's Trumpet is the shell Hawaiian's blow to start the luau.  One can only hope that this guy avoids the canned poi circuit and lives long to make lots of baby tritons.

jeff