Echinoderms are My Friends (and Cnidarians Aren't)

Spotted Linckia Linckia multifora  (Comet)  Kailua Pier 2012

    This winter we haven't seen a grat number of memorable invertebrates.  A few crabs, perhaps, but echinoderms have been in short supply.  The Kona coast is home to about five diferent sea urchins that we encounter regualrly.  And Crown of Thorns Starfish is seen routinely at deeper water sites like Kona Makai.  I hadn't seen any other starfish until about a week ago.  Not a one!       
   Snorkeling at the pier, my eye was caught by a flash of mottled red that turned out to be a small Linckia starfish, replete with violet tips that remind me of toe nails.  This little fella, maybe only three inches across, was hiding under the edge of a coral head in about two feet of water.  This is the sea star most comonly seen by snorkelers in Hawaii.  It eats algae and commonly reproduces by automotizing, shedding an arm which becomes a new organism.  Don't try this yourself at home.  The resultant four armed parent is called a comet.  Note that the fellow we found appears to have only four arms. So young to be a mother!

Cushion Star Culcita novaeguinea, Ho'okena 2012

     Yesterday we went to Ho'okena.  Despite the fact that it was drrizzling on the drive down, the beach was mobbed.  It was nice and cool as Sandra and I worked our way through the teeming throng.  We got in at the far end of the beach through some mild surf, careful not to interact with submerged rocks, and we were soon underway.  The water was cold and clear.  Almost immediately I spotted a Cushion Starfish.  He was a nice fat fellow living among the coral and rubble in about ten feet of water.  As you can see, these guys retain their pentagonal shape but don't really have arms like most sea stars.  They feed by projecting their stomachs into coral and digesting the polyps.  This species of sea star  is relatively uncommon while the Crown of Thorns (which dines upon the same species of cauliflower coral) is experiencing a population boom.   I believe this is only the third of these unusual echinoderms that I have seen in Hawaii.

Crown of Thorns Acanthaster planci  (Linnaeus 1758)

      Like me, most of you interact with invertebrates out of the water.  And aside from the odd butterfly sighting, the most memorable are attacks by small insects, mosquitoes, wasps, black flies...the list is long and distinguished.  What, you might ask, is the marine equivalent of a black fly?  Plankton!  When most of us think of plankton, we recall that certain whales eat these tiny organisms and, from the safety of our arm chair get a warm fuzzy feeling.  Mmmmm. Whales.
    Little do you know that lots of these small organisms, which aren't quite microscopic, can pack a significant sting. Sandra and I, in selecting this day for a swim at Ho'okena, had chosen to ignore the recent full moon. Our experience is that following a full moon there is a much greater concentration of stinging plankton in the water at deeper locations.  This may be associated with breeding coral (which are closely related to jellyfish and whose first life stage, is a tiny, free swimming medusa) or jellyfish swarm.

Spotted Linckia  Ho'okena, 2012

    As we swam out, hoping for another glimpse of the Flame Angelfish, we were getting into progressively denser soup with associated stings.  Accidente!
    Not only that, but we began seeing real jellyfish.  This was a species I had not seen pictured.  Swimming curled in the water, it seemed to have a superior fin while its brown string of organs curled below.  Suspended in this way, it looked like a poisonous orchid. The fact that I couldn't identify it, didn't make me want to swim with it, but it was probably a good thing ...we have been studying pictures of the highly toxic box jellyfish for a long time and this was something else.

Blue Eye Damsel Plectoglyphidon  johstonianus April 2011

      Leaving the Flame Angel to find itself, we made it back to the shoeline post haste.  There we enjoyed a swim along the shallow reef to the south of the entry.  Here we saw a Spotted Linckia, the second in about a week. This individual was about six inches from tip to tip. 
   We also saw two spring specialties.  The first was the immature of the Blue Eye Damsel.  Bright yellow tail and pectoral fin, luminous blue dorsal fin and eye.  This is a very active, small fish, difficult to photograph.  I drew a picture about thirty years ago and sent it to Jack Randall, the great Oz himself, and he wrote me back saying, "There ain't no such fish."  or words to that effect.  I took a poor picture yesterday. Luckily I've got a good picture from a year ago.  This phase may be new to the Hawaiian ichthyology literature! 
    We also saw the immature of the Freckled Face hawkfish, which is always a treat.  This too is a small furtive fish, although not as spooky as young master Blue-eye.  I hope you like the picture, even if its not perfect.

Forster's Hawkfish  Paracirrhites forsteri  Ho'okena 2012

   
    















Finally, as we were eating lunch, Sandra took a picture of a girl skipping on the rocks.  It is a charming image with which to leave you.

When you're at Ho'okena,  Life is a Day at the Beach!

jeff