Abalone development

I recently got to be a part of an abalone spawning team, where we induced abalones to release their gametes. It was very fun to see the fertilized eggs develop, and interesting for me because it was the first time that I had actually seen spiral cleavage in action! It was so different looking than radial cleavage...

I did not manage to get pictures of all of the stages, as I had to sleep, so expect some gaps. But I hope you enjoy this abalone development slide show that I put together of the stages I did see.

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.