Monthly Archives: July 2016

A preoccupied coris

The common name “coris” is applied to members of the wrasse genus of that name.  Corises resemble the other large wrasse genus Thallasoma (described in a previous post), but with slightly more protruding mouths.  There are four coris species in Hawaii and many more worldwide.

The gorgeous yellowtail coris is quite common on Hawaiian reefs.  Yellowtails eat mostly hard-bodied invertebrates that they dig out from the sand or from under rocks.  They are fairly easy to approach, but tend to take off when you dive down to the bottom to get a photo, so I mostly only manage to get photos looking down at them.  They are easiest to approach and photograph when they are preoccupied with eating.  The other day at Mahukona I ran into a female eating a small sea urchin.  She had already knocked most of the spines off the urchin by beating it against the bottom and was trying to make it more palatable by knocking it into rocks, biting it, and generally roughing it up.  This went on for a couple minutes while I hung on the surface in about six feet of water taking photos.

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A female (or initial phase) yellowtail coris trying to eat a small sea urchin while a saddle wrasse looks on, hoping for a scrap.

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This is a juvenile yellowtail coris, photographed at Hapuna Beach yesterday. While many wrasse species change coloration as they grow from juvenile to adult, the change is extreme in this species. Juveniles are fairly easy to find year round, but especially in summer.

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Here’s an older juvenile. The transition to adult coloration has begun.

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A male, also eating a sea urchin.  As with many wrasses, males are somewhat less common than females.

A threadfin returns—briefly

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Juvenile threadfin jack in the surge channel at Mahukona. Always a treat.

As noted in previous posts, juvenile threadfin jacks—or African pompano—tend to show up at Mahukona around this time of year.  They were here in July of 2011, 2012, and 2013, failing to show in 2014, and making an appearance in October 2015.  In most of these cases they were in small groups.  A solitary threadfin made a brief appearance at the beginning of this month, disappearing after just a few days.  As with the previous visits, the threadfin spent a lot of time in the shallow, usually turbid surge channel adjacent to the Mahukona dock.

Summertime Kohala

Summer has arrived on the North Kohala reefs.  Calm, clear water and abundant fish.  Water temperatures seem to be somewhat cooler than last summer when El Niño conditions led to extremely warm water and serious coral bleaching.  Let’s hope that these cooler conditions continue through the summer.

Anyway, a few days ago I spent over two hours snorkeling with my camera at Mahukona, from the dock southward past the lighthouse.  This is a relatively shallow, surgey area, usually with mediocre underwater visibility.  Conditions were very calm on this day, and visibility was good.  Here’s some of what I saw:

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Yeah, I know, I post too many photos of fivestripe wrasses. But the bar behind the eye of this one is unusually vivid.  Besides, fivestripes are among my favorite fishes, and they’re rather uncommon most places. These days I can almost always find at least one somewhere at Mahukona. I ran across this young specimen a couple hundred yards south of the dock.

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A subadult fourspot butterflyfish. You have to count the spots on both sides of the fish to get to four.

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The stately ornate butterflyfish is among the most common butterflies in North Kohala.  They almost always occur in pairs.  Almost all butterflyfish, as well as several other reef fish species, have vertical black bars across their eyes, presumably to confuse predators.  The bar does a better job of camouflaging the eye of this ornate butterfly than of the fourspot butterfly above.

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Another reef (or picasso, or wedgetail—take your pick) triggerfish.  Beautiful, common, but rather camera shy. This one was unusually cooperative.

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The gorgeous saddleback butterflyfish is rather uncommon at Mahukona, and, I understand, throughout Hawaii.  I run into a pair (I’ve never seen a solo individual) maybe once a month at Mahukona.

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A green linkia (they look blueish to me) starfish. They seem to be rather uncommon on North Kohala reefs.  Most have five legs, but this one is regenerating a recently lost sixth leg.  Leg loss is not necessarily due to predation, but is actually a means of reproduction—the lost leg becomes a new individual.  To me, starfish have a way of taking on a strangely humanoid shape, this one looking kind of like a three-legged man sprawled onto a couch looking up at the camera.

Bee liberation

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Robert holding a honey frame from a Langstroth hive. How boring.

Marla and I just returned home from almost a month in Mexico and California.  The day before returning we visited with Vanessa and Robert at their home in Rodeo.  They’ve got three bee hives in their backyard.  Two are typical commercial-style beehives, called Langstroth hives—the boxy, multilevel things we typically  think of when we think modern beehives.  Inside are arrays of rectangular frames with factory-made wax membranes stamped with little hexagons.  This setup constrains the bees to making their honeycomb and brood comb (the comb where young bees are raised) in a planar, rectangular spatial arrangement, and with cells of a pre-established size.  Langstroth hives also require use of a so-called queen excluder to prevent the hive’s queen from laying eggs in the upper section of the hive, which is intended by the beekeeper to be used for honey rather than brood.  All this facilitates mechanical harvesting of the honey and generally aids in human management of the hive.

But while humans have a penchant for rectilinearity, animals seem to prefer more free form construction.  One of Vanessa and Robert’s hives allows the resident bees to construct combs much the way they do in nature, with graceful, curvaceous catenaries.  This type of hive is called a top-bar hive.  It looks sort of like a big, elongated bird house on table legs.  Instead of frames, the inside of these top-bar hives just have a series of hanging wooden bars that the bees use as starting points for building combs.  The results, shown below, look a lot like the sort of combs you’d find in nature, in a hollow tree trunk for instance.  This system lets the bees do their own thing, deciding where to build honeycomb and where to build brood comb, how to size the hexagonal comb chambers, and how to shape the overall comb.  The down side is that top-bar hives produce less honey than Langstroth hives.  Up sides include easier, less tool-intensive honey harvest, higher wax yield, and, probably, happier, healthier bees.  The top-bar hive has been around since the seventies, but it’s new to me.  I found it so cool I had to post about it.  Thanks, V and R!

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Here Robert is holding a comb from a top-bar hive. To harvest you just shoo the bees, cut the comb off of the bar, and either mash and strain the comb or cut it up.