Grunion Development: Day 9

Not much seems to have changed from day 8 to day 9. The grunion is still the same size, and has not gained any new pigmentation. The yolk has decreased a bit, but at this point no major developmental; changes are visible. However, on day 9 they are much easier to hatch!


You can still see the remnants of the yolk in the young fish's stomach.

Grunion Development: Day 8

The eyes are fully pigment, and the body as well. The body has grown to such a length that it wraps around the inside of the egg a little over 2 times. The oil droplets have been completely depleted, and there is a little yolk left. What you can't see is that the embryo is very active, with eye and body twitches being quite common.

Grunion Development: Day 6

The embryo has grown, with the tail wrapping all the way around the egg and back around the head. The eyes have a lot of pigment and the body is starting to get a little pigment. The oil droplets are almost all used up and the yolk has a lot of blood vessels connecting it to the embryo.

Grunion Development: Day 4

The embryos are noticeably larger, and structures are becoming readily apparent. You can see the nerve cord running down the center of the embryo. gill arches forming behind the eye, and the eye itself has an indented pupil.

What you can't tell from the picture is that the heart is also nociable and pumping, and there are musculature visible along the length of the tail.

Grunion Development: Day 3

Now you can clearly see many features of the developing embryo. It has also grown large enough to wrap around the back of the egg, with the tail just peeking out on the left hand side. The oil droplets are being used up and condensed into one large drop right in the center.

Grunion Development: Day 2

Now it's approximately 37 hours after fertilization. You can still see the oil droplets off to the left, but the embryo has under gone some big changes. Instead of being a cap of cells it now has a definite form, with the head and developing eyes in the center, and the rest of the body trailing off to the top right.

Grunion Development: Day 1

I thought I'd take some pictures of grunion eggs as they develop, just because I could. Here is day 1, approximately 13 hours after fertilization. You can see the dark orange oil droplets in the center, and a pale yellow cap of cells off to the left. That is the developing embryo.

Catalina Above and Below

So I went on a trip to sample some of the sea life found around Catalina Island this past weekend. In the deeper parts we found some hag fish, which produce copious amounts of slime with the slightest provocation. The slime has microfibers in it and makes it particularly strong.

We were also lucky enough to get a deep sea octopus. This one might be a big-eye octopus, as it lacks the spots of a two-spot octo, and was caught in very deep water.

This trip was filled with all sorts of cool mollusks, like this very large black sea hare. It was probably around 13 pounds. We caught about three of these beauties. The black sea hare is the largest gastropod in the world! Luckily for me, it does not ink.

We also got a lovely navanax. The navanax is a predatory snail that follows the slime trails of other snails then swallows them whole. After digesting them, it will spit out the cleaned out shell.

We also found a couple of different types of nudibranchs. The ones pictured below are pelagic nudibranchs and are commonly found on drift wood or drift kelp. Their color depends on what they eat, with brownish individuals dining one pelagic barnacles (also in the photo) and purplish ones dining on the by the wind sailor.

We did not have any luck chumming for blue sharks this year, but we were very lucky to see this crazy critter come by our boat. Yes my favorite fish ever, the mola (or ocean sunfish) swam near our boat. Judging from the size of the fin sticking out of the water, this beauty was huge! It made my trip!

We also were lucky enough to see a variety of marine mammals. These pictured below were Risso's dolphins, the largest dolphin in our area. We also saw bottle-nose and pacific white-sided dolphins.