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Learning About Gulf of California Inhabitants

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Volunteering | Fish

Tuesday, October 02, 2007

Josie

Now, along with the end of summer has come the beginning of somewhat slower days at the Aquarium of the Pacific, since few schools have organized field trips yet and vacationers have dwindled to a handful, so we volunteers have a few weeks in which to spend more time catching up on the animals we love before we see visit with loads of children who stop by in the mornings as well as adults who stop in, some with little ones in strollers, to enjoy the somewhat less-hectic afternoons during the fall.

Right now I’m working to learn as much as I can about the fish in our Gulf of California habitat that is located upstairs, just inside from the ray pool and across from the garden eels.

We had a volunteer update on these fish a few weeks ago, and I have been returning every chance I’ve had ever since, to try to continue to identify them without, if possible, relying on what I call my “cheat sheet,” the card I have that contains most of their names and some interesting information about them.

When I was visiting the exhibit the other day, I met a woman who was photographing these fish and I mentioned one of my favorites there, the popeye catalufa (Pristigenys serrula), whose name cracks me up. This is an orange fish that has eyes that look like they are popping out of its head (I don’t think it was named after Popeye the sailor man!).

An interesting thing about the popeye catalufa is that it stays still in the water most of the time, sort of hanging there without going anywhere. Apparently, this lack of movement is a sort of camouflage because, as all other fish are swimming about, one—especially a potential predator—loses sight of those that stay still, thus saving them from becoming dinner.

This photographer asked me how she could learn more about the various fish in this habitat and, like a dope, I told her she could get information on the internet! Well, of course she could do that, but first, she reminded me, she needed the names of the individual fish! Duh!

Thankfully, I had time to spend with her, so I could point out different fish and give her their names, thanks to my little cheat sheet reference provided by our educators.

First I pointed out the Mexican lookdown (Selene brevoorti), a silvery fish that grows to 15 inches in length but is so narrow that if it is swimming toward you, it practically disappears! This fish has a steep, concave forehead-snout with long anal and dorsal fins and quite short pelvic fins.

Other fish that interested her included two beautiful ones in this exhibit, the king angelfish (Holacanthus passer) and the Cortez angelfish (Pomacanthus zonipectus), the former growing up to 14 inches in length and the latter up to 1.5 feet long.

King angelfish can be identified by a rusty brown color when they are juveniles, and by their bright blue coloring as adults; the females have yellow tail fins, while the adult males have white tail fins. An interesting aspect of these creatures is that they often act as cleaner fish for hammerhead sharks (Sphyma mokarran), eating external parasites on their bodies!

The Cortez angelfish also picks parasites off of other fishes, although I am not certain which ones they are. Adults usually are found in pairs or loose groups, while juveniles are solitary and territorial.

Another parasite eater is the Cortez rainbow wrasse (Thalassoma lucasanum) which grows to 6 inches long. It also has another interesting aspect to it: like other fish in the wrasse family, the Cortez rainbow wrasse changes sex from female to male, with the females having yellow and red stripes and the males having purple heads with yellow bands just behind their heads.

Two damselfish also are among the inhabitants of our Gulf of California habitat, these being the giant damselfish (Microspathodon dorsalis) and the Cortez damselfish (Stegastes rectifraenum). Like its name, the giant damselfish is a larger damselfish than many, growing to 12 inches in length, while the Cortez damselfish grows to only 5 inches long. The larger of the two, about which I have more information, is quite defensive if other fish or divers approach its feeding and reproductive territory.

This exhibit also holds a few spiny porcupinefish (Diodon holocanthus) that grow between 8 and 14 inches long and have strong beak-like mouths that are capable of cracking the shells of snails, sea urchins, and hermit crabs, which they love to eat. The spiny porcupinefish are distinguished from similar species by the large, dark blotches on their sides and backs. Their bodies are covered in long, sharp spines that stick out when they inflate, which they do by taking water into their bodies when they are threatened, thus forming inedible pin cushions. I sure don’t want to get bitten or stuck by one of these guys!

Another one of the inhabitants of this exhibit is the crosshatch triggerfish (Xanthichthys mento), which grows to 11 inches long and is very pretty. You can identify triggerfish by their undulating dorsal and anal fins, which they use in order to swim and which makes it look as though these fish are waving to you with two hands!

Male crosshatch triggerfish, also known as redtail triggerfish, are straw-yellow with each scale outlined in black thus creating a crosshatched appearance; they also have red tails with neon, submarginal blue bands. The females of this species also are crosshatched, but they have slate gray to blue background colors on their bodies and tails.

The woman with whom I was talking thanked me for helping her identify the fish, and I thanked her for helping me learn them better by talking to her about them.

I’m still learning, though, so I invite anyone interested to join me up there on your next visit so I can talk about them some more! Maybe I’ll have memorized a few more names by the time you stop in.

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