Do Frogs Have Backbones?

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When I was a kid and showed my pet toad to my friends, for some reason they always asked me if frogs have a backbone. The answer seemed very logical to me, who spent a lot of time observing frogs, but they would ask me if frogs had backbones, cartilage, or were invertebrates.

Although frogs have no bones during their early stages of development, they develop a backbone by the time they become froglets. Frogs are classified as vertebrates, and the complete formation of their backbones can take several weeks, depending on the species and their environmental conditions. 

While frogs have backbones as adults, my friends were right in a way, they are born without a backbone since it develops over time. Join us as we discuss frogs as vertebrates and how they transform from jelly-like eggs to structured and boned amphibians.

What Are Vertebrates or Invertebrates?

Vertebrates are all creatures and animals that have a backbone. Some well-known examples of vertebrates include fish, birds, reptiles, amphibians, and mammals.  Invertebrates are all creatures that do not have a backbone. Some well-known examples of invertebrates include worms and other bugs.

Generally speaking, there are two classes of animals on a broad scale: vertebrates and invertebrates. The identification depends on their skeletal system or lack thereof. Since frogs have bones that provide their body structure, they are vertebrates.

Frogs Are Vertebrates

All frogs have a backbone, a spinal cord, and other bones throughout their bodies to support their movement and protect their vital organs, therefore making them vertebrates. 

All frogs have bones throughout their entire body. Aquatic, arboreal, and terrestrial frogs all have these bones, although they differ in size, weight, and other physical qualities. These differentiations primarily depend on the daily habits and necessities of different species which are generally made for jumping, swimming, climbing, or digging,

Frogs have been around for millions of years, with some frog fossils dating back as far as 200 million years. While we may not know how many frog species have existed throughout Earth’s history, the surviving frog species have had ample time to develop. 

Although there are over 7,400 documented frog species to this day, frog anatomy is fairly universal. Frogs have relatively similar anatomy specifications, regardless of their size, traits, and species. This means that all frogs will eventually develop a backbone once they mature, regardless of the species, type of frog, or lifestyle.

Frog Backbone Anatomy

Frogs have 10 vertebrae. The 1st vertebra is called the atlas and it is the bone that connects to the base of the frog’s skull, allowing it to move its head. The next seven vertebrae are abdominal vertebrae as they are in the abdomen of the frog. Then are the sacrum, ileum, and urostyle.

The backbone of a frog comprises a series of nerves that run from the brain down the back, and these nerves are incredibly crucial for survival. As a result, they need to be protected from potential damage, necessitating a series of vertebrae or bones. 

The series of bones along frogs’ backs also provides increased movement. A greater range of motion is greatly beneficial to frogs, as they immediately have an advantage over less-evolved vertebrate species and invertebrates. These benefits are ideal since most frogs feed on invertebrates (insects, worms, some bugs, and other critters).

Frog Backbone Development

Frogs are born without bones as eggs laid in water. Frog eggs transform into tadpoles that develop cartilage-like structures allowing them to swim. Tadpoles eat and absorb calcium carbonate and calcium phosphate in their environment to develop bones and transform into vertebrate froglets. 

The main reason why people may believe that frogs do not have backbones is since they are not born with backbones or any bones at all. Their bones develop over time as they undergo an extensive metamorphic process. All in all, the process involves transitioning from an invertebrate-like structure to cartilage and finally to bones (CTNF).

Once tadpoles have transformed into juvenile frogs (froglets) their tail is absorbed into their bodies and they grow larger. By this phase, froglets have developed strong bones which they use to hop around and explore their environment.

Frogs Have Fused Backbone Vertebrae

Frogs have fused backbone vertebrae that allow them to propel themselves forward or upward when they jump. Having fused vertebrae allow frogs to jump aerodynamically and without causing pain in their backs due to recoil.

Very few species on Earth can transform the way frogs do, making them incredibly special and versatile. Frog backbone development is often used for scientific research, ranging from high school labs and college assignments to professional studies that could advance the medical field. 

The speed at which frogs develop depends on the species, but the phases are relatively similar until they eventually grow backbones and mature. The period may differ by a few weeks, subject to the environment and species. 

After the froglets have developed strong limb bones, backbones, ribcages, and vital organs for living on land and in water, they will continue to mature for a few years depending on the species. After this time, the mature frogs will be ready to reproduce, and the metamorphic circle of life will begin again with their offspring. 

More About Frog Backbones

Frogs have a fascinating anatomy, in part because of their bones and how they work. A frog’s hind legs and urostyle are made to help frogs leap bounds. The fact that their vertebrae are fused make it much less painful and more aerodynamic for them to jump compared to humans. Frogs are also uniquely born without backbones and develop over time.

Learn even more about frogs, their anatomy and bones in these guides on our blog:

Common Questions About Frog Backbones

Does a frog have a backbone?  Frogs have backbones by the time they are froglets with 10 fused vertebrae. Frogs are classified as vertebrates, and the complete formation of their backbones can take several weeks, depending on the species and their environmental conditions. 

Are frogs vertebrates or invertebrates? All frogs are vertebrates with a backbone, a spinal cord, and other bones throughout their bodies to support their movement and protect their vital organs.

Are frogs asexual? Frogs are not asexual since they reproduce sexually by amplexus during mating season. Frogs can be male, female, or intersex (display traits of both sexes), and some frogs can experience sex reversal based on water contaminants as well as weather and temperature in pristine conditions.

Is a frog a vertebrate yes or no? Frogs are vertebrates.