Vertebrates Vs  Invertebrates

 Know in one minute about Vertebrates Vs  Invertebrates

  • Vertebrates Vs  Invertebrates are two major categories of animals based on the presence or absence of a backbone or spinal column
  • Vertebrates are animals with a backbone or spinal column, exhibiting bilateral symmetry, having an endoskeleton made of bone or cartilage, and typically possessing a complex nervous system and closed circulatory system.
  • Invertebrates, on the other hand, lack a backbone, can exhibit bilateral or radial symmetry, may have an exoskeleton, and their nervous and circulatory systems can vary greatly
  • Both vertebrates and invertebrates play important roles in ecosystems and have diverse forms, adaptations, and ecological niches.
  • They exhibit a wide range of characteristics, behaviors, and life cycles, and contribute to the overall biodiversity and balance of natural ecosystems.


The animal kingdom is divided into two broad categories that are vertebrates and invertebrates. If you’ve ever wondered where we fall on the scale of vertebrates vs invertebrates, the answer is in your backbone. Vertebrates have a backbone, also known as a notochord, while invertebrates don’t. In this article, we are going to further differentiate these two categories of organisms Vertebrates Vs  Invertebrates in detail.


Vertebrates are organisms that possess a vertebral column also known as notochord at any point in their lives. It means having a notochord at any point during an organism’s development is enough to classify it as a vertebrate.

The vertebral column is also known as the spinal column, which is composed of individual vertebrae. The vertebrae, which can be either made of bone or cartilage, are responsible for constructing the backbone or spinal column.

Characteristics of vertebrates

1. Presence of backbone or spinal column

This structure provides support and protection to the spinal cord, which is a part of the nervous system.

2. Bilateral symmetry

Vertebrates exhibit bilateral symmetry, which means that their bodies can be divided into two similar halves along a central axis.

3. Well-developed nervous system

Vertebrates typically have a centralized nervous system, which includes a brain and spinal cord. This intricate nervous system enables advanced sensory perception, motor coordination, and behavior.

4. Closed circulatory system

Vertebrates have a closed circulatory system, which includes a heart and blood vessels. Blood is circulated through the body in a closed loop, allowing for efficient oxygen and nutrient transport.

5. Respiration through specialized organs

Vertebrates have specialized respiratory organs such as lungs or gills, which allow for the exchange of gases, such as oxygen and carbon dioxide, with the environment.

6. Advanced sensory organs

Vertebrates often possess well-developed sensory organs, such as eyes, ears, noses, and touch receptors. This allows them to perceive their environment and respond to stimuli.

7. Reproductive diversity

Vertebrates exhibit diverse reproductive methods, including sexual reproduction with internal or external fertilisation, and a range of reproductive strategies such as oviparity (laying eggs) and viviparity (live birth).

8. Diverse body plans

Body plan refers to the overall structural organization and arrangement of body parts in animals, including features such as symmetry, segments, appendages, skeleton, body shape, and organ systems.

Vertebrates exhibit a wide range of body plans, including fish, amphibians, reptiles, birds, and mammals, with varied anatomical structures, physiological processes, and ecological roles.

These characteristics collectively make vertebrates a diverse and successful group of animals that occupy a wide range of habitats on Earth, including aquatic, terrestrial, and aerial environments (1).


Invertebrates are organisms that do not have a backbone or spinal column in their body structure. They make up the majority of animal species on Earth and are incredibly diverse in terms of their anatomy, physiology, and ecological roles (2).

Characteristics of Invertebrates

They are cold-blooded animals meaning their body temperature is regulated by their external environment rather than by internal metabolic processes.

  • They possess solid, external skeletons or hydrostatic skeletons.
  • Most animals on the planet (95 percent of all animal species) are invertebrates.
  • The majority of invertebrates, except insects, are aquatic animals.
  • Invertebrates include animals from several phyla, such as Arthropoda (e.g., insects, spiders, crustaceans), Mollusca (e.g., snails, clams, squid), Porifera (sponges), Cnidaria (e.g., jellyfish, corals), Echinodermata (e.g., starfish, sea urchins), and many others. 

Vertebrates vs Invertebrates differences (3)





Animals with a backbone

-Provides support and protection –
-Encases and protects the spinal cord

Animals without a backbone            -Lack of support and protection
-Nervous tissue runs along the body surface


Fish, amphibians, reptiles, birds, mammals Insects, spiders, crustaceans, mollusks, worms

Nervous system

  • Centralized nervous system with a brain and spinal cord.
  • Enables more sophisticated behavior.
  • Enables learning and memory.
  • Can hear sounds and perceive colors.
  • Enables communication and detection.
  • Decentralized nervous system with ganglia or nerve net.
  • Limited behavioral complexity.
  • Limited learning and memory capabilities.
  • May have limited sensory abilities.
  • Limits communication and detection abilities.


  • The internal skeleton is made of bone or cartilage.
  • Provides structural support and shape.
  • Allows for growth and movement.
  • Protects internal organs.
  • External or no skeleton.
  • Provides support and protection.
  • Restricts growth and movement.
  • Limits body size and complexity.


  • Sexual reproduction with internal fertilization
  • Sexual or asexual reproduction


  • Gills, lungs, or both.
  • Enables more efficient respiration
    Enables adaptation to various environments
  • Diffusion or tracheae.
  • Limits body size and activity level.
  • Limits adaptation to aquatic or terrestrial habitats


  • Muscles attached to the internal skeleton
  • Muscles attached to the exoskeleton or body wall


  • Bilateral symmetry.
  • The body can be divided into two halves.
  • Allows for more coordinated movement.
  • Enables the evolution of specialized structures
  • Radial or no symmetry
  • The body can be divided into equal parts.
  • Allows for less coordinated movement.
  • Enables a more modular body plan

Digestive system

  • Complete digestive system with mouth, stomach, and intestines.
  • Have specialized teeth for eating
  • Enables efficient food processing
  • Incomplete Digestive system with a single opening for food and waste. May have simple or no teeth.
  • Limits food choices and processing abilities

Circulatory system

  • A closed circulatory system with a heart and blood vessels.
  • Most have a Two/Three/Four chambered heart.
  • Enables more efficient oxygen delivery
  • High levels of activity
  • The open circulatory system with no heart or vessels.
  • Limits body size and activity level.
  • Also limits activity levels and metabolic rate

Body temperature

  • Can be warm-blooded (endothermic) or cold-blooded (ectothermic).
  • Regulate body temperature internally.
  • Enables adaptation to various environments
  • Cold-blooded (ectothermic).
  • Body temperature is regulated by the environment.
  • Limited ability to adapt to changing conditions


  • Can range from small to large
  • Usually small to medium-sized


  • Can inhabit a variety of environments, from aquatic to terrestrial
  • Mostly inhabit aquatic and terrestrial

 Vertebrates vs Invertebrates similarities





Bilateral symmetry May exhibit bilateral or radial symmetry

Nervous System

Well-developed nervous system The nervous system varies in complexity

Circulatory System

Closed circulatory system Circulatory system varies in complexity

Body Plan

Highly diverse body plans and structures Highly diverse body plans and structures


Can inhabit diverse habitats such as land, water, and air Can inhabit diverse habitats such as land, water, and air

Ecological Roles

Play important ecological roles as predators, prey, pollinators, etc. Play important ecological roles as predators, prey, decomposers, etc.


1. Are Fishes invertebrates or vertebrates?

Fishes are vertebrates and are typically divided into three groups: superclass Agnatha (jawless fishes), class Chondrichthyes (cartilaginous fishes), and superclass Osteichthyes (bony fishes).

 2. Are Sharks vertebrates or invertebrates?

Sharks are vertebrates, belonging to the class Chondrichthyes, which includes cartilaginous fish and are characterized by having a skeleton made of cartilage rather than bone

3. Are Frogs vertebrates or invertebrates?

Frogs are vertebrates, belonging to the class Amphibia, which is a group of animals that includes frogs, toads, salamanders, and caecilians

4. How many vertebrate species are there?

 The exact number of vertebrate species is uncertain due to ongoing discoveries of new species. However, currently, there are estimated to be around 50,000 living species of vertebrates. Among them, fish make up the largest group with approximately 25,988 species, followed by mammals with 4,500 species, birds with 9,100 species, reptiles with 7,082 species, and amphibians with 4,880 species.

5. Are Insects vertebrates or invertebrates?

Insects are invertebrates, meaning they do not possess a backbone or spinal column. They belong to the phylum Arthropoda

6. Are Turtles vertebrates or invertebrates?

Turtles are vertebrates belonging to the class Reptilia. Turtles have a hard, protective shell made of bony plates that house their body and organs, and their backbone is part of their endoskeleton, which is a defining characteristic of vertebrates.

Written By: Deva Singh

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