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Are Frogs Vertebrates or Invertebrates?

So are frogs vertebrates or invertebrates? Well, frogs are vertebrates along with all other amphibians.

So what is a vertebrate and what is an invertebrate? A vertebrate includes all animals that have backbones.

These include fish, amphibians, reptiles, birds, and mammals. Frogs are amphibians and as such are vertebrates and have backbones.

Invertebrates include animals that do not have backbones or vertebral columns it is estimated that about 97% of all animal species are invertebrates, however, the frog isn’t one. Frogs belong to the order Anura and are the most diverse and widespread order of the class Amphibia (which includes all amphibians).

There are 35 families and over 4,000 frog species. More species are being discovered every day.

Table of Contents

1. What’s a Frog?
2. Spinal Cords and Backbones
3. Spine
4. Cartilage or Bone
5. FAQ
6. Conclusion

What is a Frog?

Edible frog (Rana esculenta) isolated on a white background
Edible frog (Rana esculenta) isolated on a white background facing the camera.

Frogs are species that belong to the order Anura. Frogs are short-bodied, tailless amphibians that are largely carnivorous. The earliest frogs (Triadobatrachus) may have existed as far back as 256 million years ago.

These amphibians can be found in subarctic zones, temperate zones, subtropical zones, and tropics. Most frogs can however be found in the tropics, specifically tropical rainforests.

Most amphibian species are frogs with frogs making up almost 90% (currently around 88%) of all amphibian species. They are also among the most diverse vertebrate orders.

Interestingly toads are also frogs and there is no scientific distinction. Toads refer to warty frog species which mostly belong to the family Bufonidae.

Toads have large bumps, short legs, and dey leathery skins. Toads are also sometimes considered to be more terrestrial.

In recent times frogs have become popular pet choices. Some popular frog species kept as pets are the African bullfrog, Burmese chubby, bumblebee dart, African dwarf, American toad, American green tree frog, oriental fire-bellied toad, Pacman frog, amazon milk frog, and tomato frog.

Do frogs have spinal cords and backbones?

Edible frog (Rana esculenta) isolated on a white background facing away from the camera
.Edible frog (Rana esculenta) isolated on a white background facing away from the camera.

Since frogs are vertebrates, then they do have both spinal cords as well as spines or backbones. This backbone can also be called vertebral columns.

In fact, frogs have a skeletal structure that is similar to that of humans and other vertebrates for that matter. The backbone connects the other bones into one system.

The backbone supports the entire skeletal structure of the frog. The backbone can be defined as a series of vertebrae (bones that make up the backbone) that extends from the skull to the pelvis. The backbone is also called the spine.

Since frogs are vertebrates, they also have a spinal cord. This is a long structure of nerves that extends from the brain and goes through the vertebral column.

The brain and the spinal cord are together referred to as the central nervous system. Frogs have ten pairs of spinal nerves.

These nerves pass information from the brain through the spinal cord. In contrast, humans have twelve pairs of spinal nerves.

Of course, as you may already know or have already guessed, the spinal cords (spinal nerves) run from the brain all the way through the backbone.

The backbone covers the nerves and is protected that way. The bones that protect the nerves are referred to as vertebrae. A series of vertebrae come together to create the backbone. 

Simply put, the spinal cord is inside the backbone (spine). Below is an adult frog’s backbone and skeleton.

frog skeleton drawing
Drawing of a Frog Skeleton.

The backbone is essential to the locomotion of the frog. It supports the entire skeletal structure of the frog and by extension, the entire frog.

The head, chest, and limbs are all connected to the backbone.

The Frog’s Spine

The frog’s spine or backbone consists of several bones. These bones are labeled as atlas, typical vertebra, amphicoelous, and sacral vertebra.

Atlas and Typical Vertebra

The atlas is the topmost bone of the spine. With frogs, the atlas is the singular cervical vertebra. Together with the atlas, there are 8 vertebrae. The other 7 vertebrae apart from the atlas look very similar and are referred to as the typical vertebra.

Amphicoelous 

The next vertebra is the amphicoelous vertebra. This bone is concave on both sides. Sacra; vertebra is right behind the amphicoelous.

Sacral Vertebra

This is the last bone of the spine. This bone is behind the amphicoelous. After the amphicoelous comes the urostyle. The urostyle is a long bone that is found at the base of the spine.

Cartilage or Bone (From Tadpole to Frog)

Life Cycle of a Frog
Life Cycle of a Frog

Frogs start life as eggs which become tadpoles. So do tadpoles have bones? Instead of bones, tadpoles have cartilage and soft tissue. These will then turn into bone as the tadpole develops into a frog.

So since the tadpole doesn’t have bones does it have a backbone?

While the tadpole doesn’t have bones, it still has a form of backbone, to be specific a notochord. In frogs, the notochord develops into the spinal column.

When hatched, tadpoles have a notochord and cartilage, and soft tissue. As the tadpole grows, it develops back limbs, and then front limbs.

From there the tadpole loses its tail. From there the tadpole which is now a froglet develops lungs. The frog can then leave the water.

By the time the tadpole has developed into a frog, the cartilage and soft tissue would have become bone through a process known as ossification.

Frequently Asked Questions

What makes frogs vertebrates?

As established in the article, frogs are vertebrates and not invertebrates. So what makes frogs vertebrates?

Well, it is the presence of a backbone. Frogs have backbones so they are vertebrates. What about tadpoles, are they vertebrates since they don’t have bones?

Tadpoles are vertebrates since they possess notochords that turn into the spinal cord and a spine.

What is the taxonomic classification of frogs? 

Frogs are amphibians of the order Anura. Anura belongs to the class amphibia which includes all amphibians. Amphibia belong to the phylum Chordata.

This phylum includes all animals that have a notochord during part or all of their lifespan. Chordata belongs to the kingdom Animalia which includes all animals. Animalia belongs to the domain Eukarya.

Eukarya → Animalia → Chordata → Amphibia → Anura

Do tadpoles have backbones?

Technically tadpoles do not have backbones.

However, tadpoles have notochords which are precursors to backbones. The notochord develops into a spinal cord and the soft tissues around it develop into the backbone.

Conclusion

Frogs are vertebrates. This means that frogs have backbones.

Frogs being vertebrates can also be described as having a notochord during some portion of their life. The notochord later develops into the spinal column.

The backbone of a frog is made up of an atlas which is the cervical vertebra; the typical vertebra which is made of 7 bones; the amphicoelous which comes after the typical vertebra; and finally the sacral vertebra which is behind the amphicoelous. There is a bone called urostyle found at the base of the backbone.

Frogs are animals of the order Anura. Frogs also include toads.

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