Category Archives: Marine Invertebrates

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.

Triton’s trumpet

Triton’s trumpets are snails and their shells are the second largest in the Indo-Pacific. They can attain a length of 20 inches. The colorful shells are also quite beautiful, especially when they catch the light filtering down from above.

These snails eat echinoderms including Crown-of-Thorns stars, which feed on corals.