I wanted to show you guys some photos of this spawning fertilization process. Two nights ago the Acropora tenuis spawned, which I showed you in the previous post. Once those gametes were collected from the surface of the water, they were carefully put into bins for fertilization. 

Fertilization bin! All those little red dots are the A. tenuis eggs. You can see just how many there are. 

Here are some more pics of the eggs being fertilized:

Babies in the making!

You have to let them sit in these fertilization bins for ~2 hours. This allows for the sperm to penetrate and for the first cell division to happen. The way you check for successful fertilization is to look at the eggs under the microscope and observe if any cleavage has happened.

Successful fertilization! You can see some of the eggs have divided into two cells (they kinda look butt-shaped....).

Eggs have been fertilized! 

These eggs are not the ones I will use for my experiments, but show the exciting process of coral sex! I'm still waiting for my Acropora millepora colonies to spawn, we're all hoping for tonight.

If you guys/girls could take a moment and think about how cool this process is. Coral sex occurs through external fertilization (outside the animal), much like a lot of aquatic animals, such as fishes and other invertebrates. Humans, as you probably know, have sex through internal fertilization (inside the animal). Corals also are able to clonaly reproduce (asexual reproduction). These eggs for example, will develop into a single polyp and then bud off other genetically identical polyps (if you want to learn about how exactly this happens, take developmental biology in college!).

Let's think about why sex exists for a moment. Evolutionarily speaking, it's more advantageous to pass on 100% of your genes to your offspring (asexual reproduction), rather than only giving them 50%. So why don't we all reproduce asexually if it appears to be more advantageous evolutionarily? Why do you some organisms asexually reproduce, some sexually and some both? What are the advantages or disadvantages to these strategies?

The question of why sexual reproduction is advantageous is an area of current research (which is very interesting, no?). I found this short essay on the topic if you happen to be interested: http://www.pbs.org/wgbh/evolution/sex/advantage/index.html.

Essentially there are two main hypotheses, sex is advantageous because it purges deleterious mutations out of the population, and it helps us fight diseases (The 'Red Queen' hypothesis) http://www.pbs.org/wgbh/evolution/sex/advantage/page03.html. As the essay states, "Sex is needed to fight diseases!". If you are interested in learning more about this, go ahead and do some of your own research on the Red Queen hypothesis, which is essential background if you want to understand the immune system and developing ways to fight diseases. Very cool!