Trumpet Fish, Key Largo, 2018, SeaLife Micro

Notes on the Innovation and Diversity of Coral Reef Fishes

It’s been a while! I’m going through my old college notes, from back when the Meg was still around. I came across these notes I apparently took on March 30, 2012, in a lecture by Peter Wainwright, and I thought they would fit in nicely in my nerdy underwater science blog section. Feel free to correct me if any information is wrong or outdated.

(As of the time of this lecture) There is more coral cover now than ever before. Reefs are a “model in biodiversity”. Most reefs are inhabited by percomorphs, “spiny-rayed fishes”, which include seahorses, cichlids, wrasse, and pufferfish, amongst many others. Almost all coral reefs also provide a home to moray eels.

Teleost fishes are the bony fishes, and make up the majority of fish species as well as almost HALF of all vertebrate species. I was recently talking to someone about my marine biologist turned nursing student life, and how I even got into fish studies in the first place. In a nutshell, while I was working on my bachelor’s degree in Louisiana, I worked at this little bar where the bio grad students and the professors would frequent every Friday. As I got to know them, I realized most of them worked for one professor in particular, the head of the Ichthyology department (fish studies). Young me asked why in God’s name there was so much interest in fish. The answer I got was, “I mean. They’re the most diverse vertebrate species on the planet. You can’t not be interested.”

Anyway. So, a subgroup of teleost fishes are the labrid fishes. These include wrasse and parrot fish. There are about 600 labrid species and exist in virtually every tropical niche, in coral and rocky reefs worldwide. They swim the way that birds fly, “flapping” their fins to generate lift (not by wagging their tails). They are also built the way a canoe is made to create drag.


Parrot Fish, Key Largo, 2017
Parrot Fish, Key Largo, 2017


Fishes living in faster moving water have higher aspect ratio fins. (Aspect ratio is the dorsal to ventral, or top to bottoms, length, divided by the anterior to posterior width (front to back)). A high aspect ratio means that the thrust the fish produces relative to drag is high (think of tuna and swordfish).

[Note: Thalassoma is a genus of wrasses; found in high energy reefs (where waves crash). “Reef crest”.] (Idk why this is in my notes but I guess I found it interesting at the time).

Most bony fish are suction feeders.

Trumpet fish are related to sea horses (and we see these all over Key Largo. They’re kinda dumb but also cute).

In eels, pharyngeal jaws sit behind the head and actually come forward to pull food in. Or to bite your finger when you’re being dumb underwater. *That was my fault. Wear your gloves.*


Eel bite in 2017
Eel bite in 2017


Parrotfish Innovations

Pharyngeal Jaw (all intramandibular joint). It’s considered “double-jointed”, not “sling jaw”. Similar types of joints and other modifications are seen in other teleost fishes. This characteristic is widely thought to promote diversity. Interestingly, variations in this type of jaw aren’t seen in data to have promoted different food sources. Parrotfish all tend to eat the same stuff. Click here for more information about parrotfish jaws, if you’re so inclined.

I also have written the question: Low nutrient environments and high biodiversity?

But I never went anywhere with it. So there you have it! My scribbled notes from a lecture on coral reef fishes. You’ve been spared the excessive doodling in my actual notes. Apparently I was into Dragon Ball and Princess Mononoke a lot at the time.

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