Thursday, March 19, 2009
Life Photo Meme: Quiet
These are grunion (Leuresthes tenuis). Found off the coast of California, these fish breed from March to July. Approximately three days after the full and new moons, these fish throw themselves on the sandy beaches of southern CA to lay their eggs. Any noise causes them to quickly flop back into the ocean.
Females bury themselves upright in the sand, while males lay on top of the sand next to the females. After the eggs are laid in the sand and fertilized, both sexes return to the ocean. The female can lay up to 3,000 eggs on a single night, and will return to the beach each time the tide is right.
Eggs take about 9 days to develop, but won't hatch until the waves from the high tides break them open, about 12 to 14 days later. Here is a picture of the developing eggs at about 6 days of age. You can already see the well-developed eyes.
If you were to look at these eggs under a microscope you can also see small red blood cells flowing through the blood vessels covering the yolk. You can also see the heart beating ( in this video, it looks like the heart is above the eyes). The tail and its associated muscles are also well developed and serve to move the small fish around in its egg.