Keri's+Second+Visit

I went on Friday, October 31, at 12:30pm.

__**Free Journal:**__ My role is to observe the animals in the ocean. When I visited, the tide was low. The water was murky and cold, even though it was a hot sunny day. When I was swimming in the water, some of the animals I saw were the raccoon butterflyfish (kikakapu), whitesaddle goatfish (kumu), convict tangs (manini), Picasso triggerfish (humuhumu-nukunuku-a-pua’a), elegant coris (hinalea), and sea cucumbers. I could not approach the fish too closely. They swam fast, but didn’t dart away from me. They were just out-of-reach. The fish swam in clusters and were not by themselves. They hovered and surrounded rocks and seaweed. Seaweed covered most of the bottom on the sides of the inlet.

I had a difficult time taking pictures of them though, except the sea cucumbers. They didn’t move at all and rested on the bottom. They were the only ones that had a camouflage because they looked like rocks.

All of the fish were noticeable and did not camouflage within their surroundings. A few of them were even brightly colored. I was wondering why they don’t blend in because being noticeable would make them vulnerable to predators.

I noticed the fish preferred living in high currents instead of the low currents. Most of the fish were at the mouth of the inlet and while I swam further into the cove, where the water was calmer, I saw less fish and eventually there was none. Why is that?

The fish were relatively the same size. They were small and appeared to be about two to four inches long. Why are they generally small? Why are the fish about the same size? I would think that there would be a range of different sizes amongst the various species of fish.

There was reef along all the sides of the inlet and it was sandy in the middle. I noticed the fish were only swimming on the sides of the inlet and none were in the middle. Why is that?

The depth of the water was about four to six feet. The fish swam on the bottom only. There were no animals swimming in the middle or on the top of the water. Why is that?

When I entered the water, the first thing I saw was this weird stringy-looking worm thing. It looked like skinny white spaghetti. I thought it was worms, but I’m not sure. It was coming from the seaweed and when I touched them, they all retracted and disappeared into the seaweed. What are the skinny white worm things?

__**Assigned Journal:**__ Specific predatory pressures were not evident so I think fishing and netting are the main predator pressures on fish, blennies, gobies, and black crabs because these organisms can swim, jump, crawl, and dart super fast under rocks and in crevices. Other predators could have drove black crabs to camouflage among the black lava rocks, forced sea cucumbers to look like rocks, and pressured hermit crabs to live in shells. Predators could have also pressured purple urchins to have a very hard shell and to live only on the rocks where the waves are the roughest.

The environmental pressures that drive natural selection are the current, tide, and waves. Current forces fish to swim fast and withstand the current itself. Tides drive pipipi and periwinkle slugs to live out of the water. They have the ability to hold enough water to survive on land. Waves made crabs to hold on to the rock when a wave crashes on them.

I think the purple urchins became more fit when they moved on the rocks where the waves are the roughest because they are the only organisms that can live on those rocks so there is no competition. There’s more space, food, and minimal predators. The very hard shell makes the purple urchins fit for it helps them to withstand the rough waves.

For blennies, the ability to jump from tide pool to tide pool makes them more fit than other organisms because they can obtain more food by doing that. They also can survive longer because if the tide pool dries out the blennies could just jump over to another and they can jump away if a predator is after them. They are not stuck in one place.

Camouflage is a heritable variation amongst the crabs and sea cucumbers. And it is especially a good one for the sea cucumbers because they move awfully slow and if they are seen, they are doomed. Camouflage makes both the crabs and sea cucumbers more fit to survive because it makes them unseen from predators.

Some fish are brightly colored. I don’t think this heritable variation makes them more fit because they are easily seen by their predators. But at the same time, being brightly colored could make them more fit because I think this would be advantageous when reproducing. The bright colors attract mates and sexual selection would occur. This situation is just like the peacocks.