When you think of sharks, you probably think of ferocious predators that are closely related to fish. But what you might not know is that bony fish are actually more closely related to humans than they are to sharks.
Cartilaginous fish, which include sharks and rays, are actually more closely related to mammals than they are to bony fish. So, do sharks have backbone or vertebrae?
Sharks do have a backbone and the backbone of a shark is made up of cartilage, which is a tough and flexible material. This material helps sharks move quickly through the water and helps them stay upright in the ocean.
Do Sharks Have Backbone
Sharks are a member of a different group of fish from the class chondrichthyes. Literally, this is the only class in the phylum Chordata, which includes sharks, skates, rays, and several other smaller (holocephalis) and oddly shaped fish.
So, do sharks have bone?
They are distinguished by their skeletons, which are made of cartilage rather than bone. Chondrichthyes are some of the oldest fish on Earth, and today there are more than 1,000 species.
Cartilage is a type of connective tissue that helps make up the skeleton. Cartilage is found in areas such as the nose, ears, and joints. It is a flexible and smooth material that helps cushion these areas. Cartilage is also relatively strong and can withstand a good deal of pressure.
Cartilages are tougher and more flexible than bone, which makes them well-suited for swimming.
Although other animals have boney cartilage with a similar structure, shark cartilage contains a greater variety of fused cells. Different from other animals, sharks’ cartilage is primarily calcified. The areas of calcification in the cartilage of sharks house several types of vital and non-hypertrophic cells.
Creditheadichthyans and osteichthyans split into two species around 400 million years ago. The symbiotic coexistence of sharks and other clasped fish has lasted through the ages, resulting in various unique physical traits.
Benefits of Sharks Cartilaginous Skeleton
The cartilaginous skeleton has a number of benefits over the bony skeleton. Cartilage is more flexible than bone, and so can better withstand stress and shocks. This makes it better suited for tasks such as movement and cushioning.
Cartilage is also lighter than bone, making the cartilaginous skeleton less dense and therefore more buoyant. This can be advantageous in aquatic creatures who need to stay afloat.
Finally, cartilage is able to regenerate more easily than bone, meaning that injuries are less likely to cause long-term damage.
Why is a Shark Skeleton Made of Cartilage?
Sharks skeletons are made of cartilage for a few reasons.
Cartilage is a lot lighter than bone, so it makes sharks faster and more agile in the water. Cartilage is also a lot more flexible than bone, which allows sharks to turn their heads quickly and swim through tight spaces.
Finally, cartilage doesn’t corrode in salt water like bone does, so it lasts a lot longer underwater.
Do Sharks Have Rib Cages?
Sharks are a group of fish that have a number of anatomical features that set them apart from other fish. One of these features is their rib cage.
Sharks do not have true ribs like most other animals. Instead, they have cartilaginous rib cages that are made up of flexible connective tissue.
This allows sharks to move their bodies more easily and swim faster.
Do Sharks Eat Bones?
Sharks can and do eat bone. While they primarily consume the flesh of their prey, sharks are known to ingest bones, cartilage, and other harder parts of their victims.
Shark diets can vary depending on the species, but many sharks are opportunistic feeders and will consume a wide range of marine animals, including fish, seals, sea turtles, and even other sharks.
Sharks have powerful digestive systems with strong stomach acids and enzymes that enable them to break down not only the soft tissues of their prey but also the harder components like bones and cartilage. These tougher parts can be digested over time, ensuring that the shark extracts as much nutrition as possible from its meal.
References
- Moss, Melvin L. “Skeletal tissues in sharks.” American Zoologist 17.2 (1977): 335-342.
- Wainwright, Steve. “Shark backbone: Structure and function.” Journal of Biomechanics 13.2 (1980): 197.
- Wainwright, S. A., F. Vosburgh, and J. H. Hebrank. “Shark skin: function in locomotion.” Science 202.4369 (1978): 747-749.
- Ebert, David A., Marc Dando, and Sarah Fowler. Sharks of the world: a complete guide. Princeton University Press, 2021.
- Caplan, Arnold I. “Cartilage.” Scientific American 251.4 (1984): 84-97.
- Eyre, D. R. “The collagens of articular cartilage.” Seminars in arthritis and rheumatism. Vol. 21. No. 3. WB Saunders, 1991.
