Category Archives: Marine Invertebrates

The morning dip

A whitetip reef shark passes below looking, I think, for a quiet place to get some rest.
A fourspot butterflyfish swims by a patch of cauliflower coral, some living, some dead. There are two spots on each side, but this fish was very small so the second spot was still filling in as space allowed.
A blue goatfish cruises by.
A green linckia sea star and lobster molt. Most green linckia have five arms but can have four or six. They’re able to reproduce by detaching an arm which will eventually develop into a new star.

This week’s Friendly Friday challenge theme is ‘Morning Rituals.’ See more responses here.

Most mornings, I try to get in the water, as conditions and schedules allow. Morning is the best time for snorkeling as the water is usually calmer before the wind picks up as the day wears on. Visibility can vary from day to day and it can help to check surf reports to see if there are any swells moving in. But calm water doesn’t guarantee good visibility just as swells don’t always mean bad visibility. There’s only one way to be sure and that’s to jump in.

My favorite thing about snorkeling is that every day is different and I never know what I’ll see. Going to the same spot means I become familiar with some of the regulars, but there are always transient creatures passing through including rays and dolphins. And while those big creatures are great to encounter, it’s equally interesting to watch the activities of smaller fish and marine invertebrates.

It’s a rare day indeed that I don’t emerge prattling on about something I saw while I was in the water. And on those rare days, well, I’ve still had a good swim to set me up for the day ahead.

It wasn’t until I processed this photo of a goldring surgeonfish that I noticed the stocky hawkfish resting motionless below it.

Clumpy nudibranch

My local snorkeling spot has been roiled with excitement lately over the appearance of a couple of clumpy nudibranchs. Well, it’s exciting for us.

Nudibranchs (pronounced noo-di-branks or noo-da-branks) are members of the sea slug family. Granted this doesn’t sound too exciting, but nudibranchs are strange and exotic and often wildly colorful. The reason I haven’t posted photos of a nudibranch before is that I’ve never seen one before, let alone got a photo of one. That’s the downside of nudibranchs; they tend to be on the small side. One to three inches is typical for most of them. But clumpy nudibranchs are big, up to 10 inches long. In nudibranch world they’re like King Kong, visible from space.

When they were first spotted, I didn’t see them, but I was on high alert. And then, one day, I saw my first nudibranch. I popped up and called to my wife, only to see her waving at me to come see the nudibranch where she was. So this established that nudibranchs are like buses; you wait and wait and wait, then two come along at the same time. Since then, I’ve seen one or both of them most days I get in the water. Each time I’ve seen either of them they’ve been motoring along at speed, at least for a slug.

Clumpy nudibranchs have some color variations which can be seen in these photos. One has more yellow coloring, the other (second photo) being browner. The order’s name, Nudibranchia, means naked gills. These are the feathery clumps to the rear of the nudibranch. The two protuberances at the front are sensory organs. Clumpy nudibranchs feed mainly on sponges (not the cake variety).

Going, going, gone

Last week I posted some octopus photos here. A few days after taking those photos, I had another octopus encounter which I enjoyed a good deal.

I swam over a rocky ledge and saw an octopus in the middle of a large, flat rock. The rock was pale, but speckled and the octopus was quite white with brown markings. When an octopus gets angry it will flush white, but that wasn’t what was happening with this one. Its paleness was an attempt to blend in.

I stopped and the octopus froze. I took a couple of photos. There was another rock a short way away with a dark area where it overlapped the rock the octopus was on. Very slowly, the octopus oozed out a tentacle toward that dark area (top photo). Once the tip reached the shadow it appeared to drop anchor. Then the body of the octopus followed, hauled along on that anchored tentacle. A few moments later, the bulk of the octopus reached the shadows and slipped from view.

It was a slow, deliberate process and I couldn’t help laughing to myself. It appeared as though the octopus hoped that by sliding off in this incremental way I wouldn’t notice its departure. Such a pretty octopus though.

What color is this octopus?

The answer to the headline is that it depends on the moment and the background. I surprised this day octopus when I came around a corner and it instantly changed color. Then it moved and changed color again. I edged away and it moved and changed color again. It changed about five times over the course of a few minutes and each change was like hitting a light switch – one moment this, next moment that.

Their default color is a gray-brown, but I didn’t see that on this occasion. The red of the center photo is a reaction to being surprised and the two mottled patterns are camouflage attempts.

Posted in response to Becky’s July Squares challenge theme of ‘Perspective.’ See more responses here.

Yesterday’s swim

A small shoal of convict tang feeding.
I think this is a spotted coral blenny on a head of purple cauliflower coral, and possibly a small trumpetfish.

This is a second response to this week’s Sunday Stills challenge theme of ‘Waterworld.’ (See more responses here.) Yesterday, I posted about the movie Waterworld. Today, it’s a probably more expected response.

These are photos I took during my swim yesterday. Visibility in the water was patchy with some good areas and some not so good. I didn’t see anything startling, though the mackerel shads aren’t a common sight. Last time I saw such a shoal there was a great barracuda lurking on the other side. I looked around and, sure enough, there was another one looking interested as it cruised low down, too low for a decent photo.

The other oddity was in the photo at left. I saw what I think is a spotted coral blenny on this patch of cauliflower coral, and snapped a quick photo before it took off. But it was only when I processed the photos that I saw something else, to the left and slightly below the blenny. I think it’s a small trumpetfish, but it could be something else. A lot of small fish and other creatures hide in coral heads so I must pay more attention from here on.

In short, it was a fairly typical swim.

A shoal of mackerel scad on the left with yellow tang on the right.
Little fish enjoy the comparative safety of the shallow water in the surge zone.
On the left, a fourspot butterflyfish and a cushion star. On the right, black triggerfish are cleaned by a Hawaiian cleaner wrasse.
Just before getting out I saw this small Pacific trumpetfish with goldring surgeonfishes.

The top of Two Step

Two Step is a popular snorkeling spot, next door to Pu’uhonua o Hōnaunau National Historical Park, otherwise known as Place of Refuge. It gets its name from one of the entry points to the water, where two flat lava ledges make it easy to get in and out. Well, fairly easy; there’s usually a crowd gathered around the steps so it can be a bit of a scrum. Also, small sea urchins sometimes lurk in hollows in the steps.

Once it the water, there’s room to roam. I like to swim the length of the bay and out a little bit, to where I can look down the coral slopes leading to the sandy floor of the bay.

Posted in response to Becky’s April Squares challenge theme of ‘Top.’ See more responses here.

Arc-eye hawkfish and bleached coral

This is a typical pose for an arc-eye hawkfish, keeping very still as it nestles in a head of cauliflower coral. But the coral is not well. This patch is mostly bleached. The causes of coral bleaching include warmer than normal water temperatures, pollution, and sunscreens containing coral-killing ingredients.

Because of this third factor, Hawaii has passed a bill which will ban the sale of sunscreens containing oxybenzone and octinoxate. This law goes into effect January 1, 2021. While this will help, it won’t do anything to keep harmful chemicals out of water runoff, and it won’t do anything to prevent the warming of the Pacific Ocean.

Last fall, we had a coral bleaching event here because of warmer ocean temperatures. It wasn’t as bad as feared, but still did damage to corals that were just recovering from previous bleaching events. There are one or two snorkeling sites here that I don’t visit anymore because the state of the coral is just too depressing. I’d like to think that this degradation can be reversed but, honestly, I’m not optimistic about that.