Even though they are a form of fish, sharks have very different body structures than common fish you might see every day. The whale shark is no different.
Like most sharks, they can have fins that function differently and different bone structure from most other fish. They also have a unique type of scales.
Whale sharks do have scales, but they’re different from regular fish scales. The scales of a whale shark are like tiny teeth called dermal denticles. They offer protection and faster swimming for the whale shark.
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Whale Shark Appearance
Whale sharks have grayish, brownish, or bluish backs with a white underbelly. Their backs also have a distinctive pattern, similar to a tiger shark except instead of stripes, whale sharks also have spots.
These markings are as unique to each whale shark as a human fingerprint.
Whale sharks, or Rhincodon typus, don’t have much genetic relation to whales, despite their name. Whale sharks, like all sharks, are cartilaginous fishes of the Orectolobiformes order.
True whales, on the other hand, are aquatic mammals and belong to the taxonomic order Cetacea.
| Species | Kingdom | Phylum | Class | Subclass | Order |
|---|---|---|---|---|---|
| Sharks | Animalia | Chordata | Chondrichthyes | Elasmobranchii | Orectolobiformes |
| Whales | Animalia | Chordata | Mammalia | Theria | Cetacea |
The size of a whale shark is what gives it its common name. They are the largest species of fish in the world and can grow up to 40 feet (12 meters) long.
They’re also filter-feeds, similar to blue whales. Whale sharks eat krill, fish eggs, and small fishes by swimming with their mouth open. This fills it with water that contains their much smaller prey.
Their mouth is at the front of their head instead of on the underside like most shark species.
They may be huge, but whale sharks aren’t very intimidating. They don’t hunt large animals like other sharks. In fact, their throat is too narrow to allow in anything bigger than a small fish.
They do have rows of replenishing teeth much like other sharks, but it’s thought that these have no feeding functionality.
All Sharks Have Scales
Scales, like teeth, are a shared feature of all shark species, including whale sharks. Fish in general typically have scales, but shark scales are unique.
The taxonomic class Osteichthyes makes up 96% of all fish species. They can have three different types of scales: cosmoid, ganoid, and cycloid/ctenoid.
Only sharks and rays of the Chondrichthyes class have what are called placoid sales.
These are also known as dermal denticles, which literally translates to “skin teeth.” This name comes from the fact that these scales have the same structure as teeth you find in a mouth.
First, there is a hard layer of enamel (vitro-dentine), a strong mineral layer called dentine, and a pulp cavity.
Dermal denticles don’t get larger as the shark grows; instead, the sharks grow more scales as they need them.
How Scales Help Whale Sharks
The scales of a whale shark benefit it in several different ways. They offer protection from the environment as well as other animals.
Their scales also make it easier for them to swim through the ocean.
Scales For Protection
One of the main benefits of a shark’s scales is protection. The placoid scales are thick and hard which can make it difficult to bite through or scratch.
Even if they’re not in a fight with another animal, things like rocks and coral could damage them if they didn’t have their scales.
The scales can even protect them against small animals – in short, parasites. The ocean is full of parasites like lampreys, mites, sea-lice, and barnacles.
The layering of a shark’s scales can help prevent various parasites from taking hold, although they don’t stop them all.
Shark scales also offer benefits for swimming. Shark scales attach to the skin at their base and end in a pointy tip called a crown.
All the tips point in the same direction, so if you rub your hand on a shark from head to tail, it will feel smooth. Rub it in the opposite direction, and it will feel as rough as sandpaper.
Scales For Swimming
This single-direction layering, along with the shape of each scale, helps direct the water currents while a shark is swimming.
They can channel water away from their noses and eyes, and away from their extra-sensory organs (electroreceptors).
Sharks have small, sensitive openings in their skin that detect electrical fields, no matter how faint. They can use these to orient themselves with the earth’s geomagnetic field.
They can also sense the electrical charges of their prey’s muscle contractions.
They also have small pores that can detect pressure changes in the water around them. This, along with their electroreceptors, are extremely important for a shark’s ability to navigate.
Having scales that can keep these sensory organs free of unnecessary water flow is vital to their movements.
Finally, shark scales reduce “frictional drag.” This is when the friction between the shark and the water slows them down.
But because of the shape of their scales, the frictional drag can reduce by up to 13 percent.
In Summary
Whale sharks have no taxonomic relation to whales at all. Though they both live in the water, whales are aquatic mammals, while whale sharks are fish that belong firmly with other species of sharks.
Like fish, whale sharks do have scales on their body, but these “dermal denticles” are unique to sharks and rays.
These tooth-like scales offer protection for the whale shark against predators as well as scratches and scrapes from their environment. They also help whale sharks swim by keeping water away from sensitive areas and reducing drag.