DIVE DRY WITH DR. BILL #728: MY EASTER EGG HUNT
On Easter Sunday I decided to visit my favorite church, the Kelp Kathedral. While all the kiddies searched for eggs left scattered through Avalon by the Easter bunny, I found mine in a slightly different habitat... the rocky reef. However, they were left there by a hare... the California sea hare Aplysia californica.
My original intent was two fold. I wanted to have my first sighting of our giant sea bass (Stereolepis gigas) this year and hoped to locate and identify a nudibranch or shell-less snail a local dive instructor had spotted on the even more wrecked Suejac. Of course I've seen hundreds of giant sea bass over the past two decades, but it is always a treat to encounter and film them. Once again I struck out on both goals.
As I finned back toward the stairs, I noticed several piles of white "strings" intertwined and attached to the rocky reef and seaweeds. The very first time I saw some of these, I thought a yachter along our coast had dropped his spaghetti dinner overboard. After that dive I quickly identified them as the eggs of the Easter bunny of the sea (aka the California sea hare) even without benefit of the Internet!
Like their relatives the nudibranchs, these snails live their lives without the protection of a hard outer shell. There is a small shell inside that protects the gills and heart, but this critter's primary defense is chemical in nature. Strictly herbivorous, this sea hare feeds primarily on several species of red algae. Not only does its diet result in the reddish to brown body color, but also in the toxins in its body.
If you grab these snails and handle them roughly (shame on you), you may have had them release a reddish-purple ink. Some scientists believe this ink serves as a screen to hide the animal from predators. They may also release a milky white cloud which contains opaline, a chemical to which many potential predators react negatively. The giant green sea anemone is a predator that only consumes part of the sea hare, ejecting it when it "chomps down" on the digestive gland. Other predators include lobster and starfish, as well as the sea hare's relative Navanax.
This species is hermaphroditic and is simultaneously both male and female. The creation of the egg masses requires at least two to tango... er, tangle... but may involve as many as one or two dozen engaged in a mating orgy. The lead sea hare functions as a female only while the ones behind "her" function as males for the sea hare in front and females for the ones behind them. According to sources, Aplysia likes to start the morning off right... and I don't mean with a cup of coffee or a donut. Mating often occurs during summer before Noon. However these orgies may last for hours, or even days.
An individual may lay up to 80 million eggs at a time. Initially they are yellow-green but in a little over a week they turn brown. The larvae which hatch live in the plankton for up to about five weeks, then they metamorphose and settle to the bottom. The juvenile stage lasts another five weeks and they reach sexual maturity 85 days after hatching. Some sources believe these sea hares live for just a single year, but individuals older than that have been observed.
Many accounts suggest that these snails gather in sea grass beds to mate and lay their eggs attached to the marine grasses. However, we have no sea grass beds in the dive park and the hares have no problem laying their eggs at the base of giant kelp, on other seaweeds or just on the reef itself.
© 2017 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: California sea hare mating cluster and fresh egg masses laid on the reef; close-up of egg masses and juvenile sea hare on blade of Eisenia kelp.
On Easter Sunday I decided to visit my favorite church, the Kelp Kathedral. While all the kiddies searched for eggs left scattered through Avalon by the Easter bunny, I found mine in a slightly different habitat... the rocky reef. However, they were left there by a hare... the California sea hare Aplysia californica.
My original intent was two fold. I wanted to have my first sighting of our giant sea bass (Stereolepis gigas) this year and hoped to locate and identify a nudibranch or shell-less snail a local dive instructor had spotted on the even more wrecked Suejac. Of course I've seen hundreds of giant sea bass over the past two decades, but it is always a treat to encounter and film them. Once again I struck out on both goals.
As I finned back toward the stairs, I noticed several piles of white "strings" intertwined and attached to the rocky reef and seaweeds. The very first time I saw some of these, I thought a yachter along our coast had dropped his spaghetti dinner overboard. After that dive I quickly identified them as the eggs of the Easter bunny of the sea (aka the California sea hare) even without benefit of the Internet!
Like their relatives the nudibranchs, these snails live their lives without the protection of a hard outer shell. There is a small shell inside that protects the gills and heart, but this critter's primary defense is chemical in nature. Strictly herbivorous, this sea hare feeds primarily on several species of red algae. Not only does its diet result in the reddish to brown body color, but also in the toxins in its body.
If you grab these snails and handle them roughly (shame on you), you may have had them release a reddish-purple ink. Some scientists believe this ink serves as a screen to hide the animal from predators. They may also release a milky white cloud which contains opaline, a chemical to which many potential predators react negatively. The giant green sea anemone is a predator that only consumes part of the sea hare, ejecting it when it "chomps down" on the digestive gland. Other predators include lobster and starfish, as well as the sea hare's relative Navanax.
This species is hermaphroditic and is simultaneously both male and female. The creation of the egg masses requires at least two to tango... er, tangle... but may involve as many as one or two dozen engaged in a mating orgy. The lead sea hare functions as a female only while the ones behind "her" function as males for the sea hare in front and females for the ones behind them. According to sources, Aplysia likes to start the morning off right... and I don't mean with a cup of coffee or a donut. Mating often occurs during summer before Noon. However these orgies may last for hours, or even days.
An individual may lay up to 80 million eggs at a time. Initially they are yellow-green but in a little over a week they turn brown. The larvae which hatch live in the plankton for up to about five weeks, then they metamorphose and settle to the bottom. The juvenile stage lasts another five weeks and they reach sexual maturity 85 days after hatching. Some sources believe these sea hares live for just a single year, but individuals older than that have been observed.
Many accounts suggest that these snails gather in sea grass beds to mate and lay their eggs attached to the marine grasses. However, we have no sea grass beds in the dive park and the hares have no problem laying their eggs at the base of giant kelp, on other seaweeds or just on the reef itself.
© 2017 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: California sea hare mating cluster and fresh egg masses laid on the reef; close-up of egg masses and juvenile sea hare on blade of Eisenia kelp.
