Post created by Gunnar
The channel TierZoo on YouTube posts informational and entertaining videos blending an interest in zoology with a love of gaming. TierZoo will use modern gaming terminology instead of high-level phylogenetic terminology to describe animal characteristics so if you do not have a gaming vocabulary it may take some time to adjust to this unique vernacular. Most of his videos involve taking a specific subsect of the animal kingdom and ranking them on a tier list to determine what is “meta” (a gaming term meaning the most powerful). Assigning items to a tier list is common practice in gaming, where tiers are arranged with F at the bottom and A at the top, similar to a school grade scale but with the addition of S tier at the top for the absolute best. The main criteria for an animal being placed highly is how well suited it fits its environment and how it matches up with other animals. For example, if we were creating a dog tier list domestic dogs not wolves would likely be the highest ranked. This is because domestic dogs have evolved to have a relationship with humans that allows them to very easily survive and thrive whereas a wolf must fight very hard just to get a meal. The criteria is not meant to be overly scientific and occasionally, TierZoo will stray from this structure but in general this is how the lists are formed.
Recently, TierZoo made a video ranking the bony fish and some of his rankings were quite surprising. Because we have just learned all about bony fish, I think it would be interesting to evaluate his tier list with a more scientific orientation. It is also important to point out that this video is only able to rank an extremely small amount of fish compared to the over 33,000 species of extant fish.
Starting at the bottom of the tier list we have two familiar fish that we have encountered in class: the sunfish and the sea horse. Using gaming vernacular these fish would be considered “low tier trash” as neither of them is very well suited for survival. Even though seahorses have a prehensile tail and are viviparous they are overall not very well evolved due to their low mobility. Sure, a tail is useful to hold onto branches, but they would not need it if they had more than 1 fin in the first place. Moreover, the seahorse is not very big, and its diet consists of mostly plankton showing us the seahorse does not have a good matchup with other fish. The other member of F tier is the ocean sunfish for a litany of reasons. Firstly, they are extremely immobile and have no real way to escape predators other than just being big, however, their size still does not stop high level ocean predators like sea lions from tearing them apart. Additionally, because the sunfish evolved to have thin mucus coated skin instead of scales it is particularly vulnerable to parasites. The sunfish does get some credit for enlisting the help of birds, wrasse and shrimp to help cleanse itself of parasites but until it evolves to swim faster, develop scales or defend itself the sunfish will remain low tier trash.
Next up in D tier we have two interesting fish: the flying fish and salmon. The flying fish has evolved to have very large pectoral fins that allow it to jump out of the water and glide for a short period of time. This ability is useful to escape predators that are much larger and faster than it but leaves it vulnerable to getting plucked out of the air by birds. To make matters worse when the flying fish does re-enter the water it is usually disoriented for a brief second, enough time for a fast-moving pelagic fish to get a meal. The other fish in D tier may be surprising to some but Salmon have some serious evolutionary shortcomings. The salmon’s high mobility might make it a candidate for a higher tier, but they have very poor interactions with non-aquatic animals like bears. Because salmon are anadromous, they are forced to swim upstream to spawn in freshwater making them extremely vulnerable to predators.
In C tier we have the catfish and archer fish. Catfish are bottom feeders and can generally find food anywhere making them suited to a wide array of environments. However, their greatest asset is the venomous barb's that they have on their pectoral fin's. This spine allows them to deter a wide variety of predators. Some birds with particularly long beaks can still skewer smaller catfish but overall, these venomous barbs are very useful for keeping the catfish alive. The more interesting member of C tier is the archer fish. This fish has evolved the extremely unique ability to spit water at insects in low hanging branches and knock them into the water. While this is quite an effective strategy, they suffer from a similar weakness to the flying fish in that they can easily be picked off by birds while at the water's surface.
In B tier we have the largemouth bass. There is not any unique or interesting ability with this fish, instead they are able to thrive because they are generally much larger than their prey and possess a rather large mouth, hence the name. Their size and mouth allow them to feed on a wide variety of prey such as other fish, insects, amphibians and even juvenile alligators. The more interesting addition to B tier is the cleaner wrasse, mentioned earlier as they clean parasites from larger fish like the sunfish. This does provide them with an easy food source; however, they are pretty much at the mercy of whatever fish they are cleaning. If the wrasse is not careful, they could easily be betrayed by a much larger predator.
In A tier we have the Muskellunge. These fish are vicious freshwater predators even known to attack mammals. They have a long-streamlined body to reduce viscous drag and powerful jaws to clamp down on prey. They can also camouflage well into grassy lake bottoms to stage an ambush. Also, in A tier is the piranha. A shoal of piranha can rip through a much larger animal with relative ease thanks to their razor-sharp teeth. TierZoo explains that the reason they are not ranked higher is due to their lack of defensive ability, but this really is not true. Like catfish, piranhas are members of the superorder Ostariophysi and release a warning pheromone when injured that warns other piranhas to stay away. Another member of A tier is the lionfish. This fish has become so well evolved that it has invaded parts of Florida and the Bahamas. Similar to the catfish, lionfish have venomous spines, however, instead of 1 on each pectoral fin the lionfish has 13 venomous spines all over its body. Despite their low mobility, lionfish have no problem finding a meal because they employ a very generalist approach to feeding, eating almost anything.
In S tier we have some impressive fish that dominate their environment with their unique abilities. First up, the moray eel is extremely well evolved to fit the coral reef ecosystem. They have razor sharp teeth and a pharyngeal jaw to rip apart prey with ease. Their slender body allows them to navigate tight cracks in coral with ease and they can even tie themselves in knots in order to leverage a fish out of a hole. Morays have a slime coating on their scale-less skin that allows them to brush up against sharp coral and even urchins without taking damage. This ability also gives the moray a favorable matchup against other high tier fish like lionfish as they are largely immune to the spines. Despite their anguilliform swimming, moray's are capable of some impressive burst's of speed as well as great maneuverability in tightly packed coral. Their vibrant colors may seem disadvantageous, but coral is full of vibrant colors so moray's blend in well. Lastly, moray's are highly intelligent, able to follow fish that hunt in open water so that they can attack small fish that get scared into the coral. Additionally, moray's are smart enough to set traps for their prey. They have been known to wait near lobsters at knight in order to attract octopus for a nice meal.
The other member of S tier is a group of fish: billfish. These fish have long, slender, scale less bodies and make use of modified carangiform swimming, making them the fastest fish in the ocean. Their large dorsal fin allows them to make tight turns and their bill allows them to capture fish at range. Combine this with their large size and you have a truly well evolved fish.
In closing, I agree with this tier list of fish. At the end of the day this is all totally subjective, but I feel that TierZoo does an excellent job of supporting his rankings with science. I also appreciate how he tends to focus on fish that are either unique or very well-known as it helps the lay person to understand his reasoning. But what do you guys think? Is the moray eel actually low tier trash? Is the sunfish actually S tier? Please leave any changes you would make to the tier list in the comments!
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