Vertebrated and invertebrated animals

The vertebrate animals are animals that have skull and spine bone or cartilage; the invertebrate animals are characterized by not having bone structures.

The Animalia kingdom in general presents these two large groups, which are internally very varied. Invertebrate animals represent the majority of animals on planet Earth. Know the differences between vertebrate and invertebrate animals, their characteristics and examples of animals in each group.





TaxonomyPhylum Chordata

Subphylum Vertebrata

Invertebrate subphyle
DefinitionAnimals with bonesBoneless animals

  • Partenogenesis
  • Gemmation
  • Fragmentation








Porifera: sponges

Cnidaria: jellyfish

Platyhelminthes: platelmintos



Echinoderms: starfish

Mollusks: snails, octopuses.

Hexapoda: insects.

SymmetryBilateralRadial: corals, jellyfish.

Asymmetric: sponges.

Number of known species69 963 speciesMore than 1 million.
Digestive systemFull
  • Diffusion
  • Intracellular digestion
  • Incomplete digestive system
Gas exchangeLungs


Gas diffusion
  • Heart with chambers
  • arteries and veins
  • Closed circulation
Open circulation
  1. Lamprey
  2. Mantaraya
  3. Fishes
  4. Salamanders
  5. Frogs
  6. Crocodile
  7. Snake
  8. Turtles
  9. Birds
  10. Dolphins
  1. Sea sponges
  2. Sea anemones
  3. Worms
  4. Leeches
  5. Snails
  6. Bees
  7. Sea stars
  8. Tunicates
  9. Octopus
  10. Spiders

What are vertebrate animals?

Vertebrate animals are eukaryotic multicellular organisms belonging to the Animalia kingdom that have a “backbone” . The spinal column comes from the notochord and protects the nerve cord.

They are heterotrophs , they obtain energy from their food, which can be plants (herbivores) or other animals (carnivores).

The name “vertebrate” derives from the Latin vertebra (joint) and this from the Latin vertere , which means to bend; So the meaning of vertebrates is that animal that has articulated vertebrae.

Characteristics of vertebrate animals

  • They belong to the Chordata phylum Vertebrata subphylum .
  • They have a skull , either made up of cartilage (eels, witch fish, and other fish), bone, or both.
  • They present a skeleton , whose central element is the vertebral column , formed by vertebrae.
  • They generally have two pairs of limbs (tetrapods: four legs).
  • Variable size : they can range from the tiny frog Eleutherodactylus iberia at just 9.8mm to the huge blue whale Balaenoptera musculus , at 30m.
  • They live in various regions of the earth : some are aquatic like fish, others are terrestrial like lions, some live in deserts, like snakes, and others inhabit frozen regions like penguins and polar bears.
  • Some vertebrates keep their body temperature constant (homeotherms), such as birds and mammals, while poikilotherms, such as lizards, can vary their temperature.
  • They have various shapes : most fish are spindle-shaped, which allows them to move with minimal resistance through the water; others are flattened in shape, like reptiles.
  • They can move by different means: air locomotion (birds and bats), land locomotion (horses and elephants), water locomotion (sharks and rays).
  • They have skin with two layers, the dermis and the epidermis, with a mainly protective function of the external environment.
  • They present adaptations in the skin such as feathers, hair and scales.
  • The cardiovascular system of vertebrates consists of the heart, veins, arteries, and blood.
  • The respiration is performed by the exchange of oxygen from the air or water into the blood and removing carbon dioxide to the outside.
  • They have a nervous and endocrine system that controls and regulates bodily functions.
  • All vertebrates have a sense of smell and hearing that allows them to find food, detect danger and find a mate.
  • Most vertebrates have eyes , although for animals that live in caves or depths it is not functional.
  • The reproduction is sexual , and depends on various factors, such as environmental temperature, the method of fertilization and development elestado animal. Most species of vertebrates have individuals with separate sexes, only some angulias and fish are hermaphrodites, that is, an individual has both female and male organs.
  • The fertilization may be external (outside the female body, and amphibians) or internal (within the female body, as in mammals and birds).
  • The mode of reproduction can be oviparous (they produce eggs) or viviparous.

Examples of vertebrate animals

1. Cyclostoma: jawless fish

Lampreys belong to the Petromyzontidae clade with approximately 35-40 species. They are known as jawless fish, with a funnel-shaped mouth with teeth.

2. Cartilaginous fish: sharks and manta rays

Sharks and manta rays belong to the Chondrichthyes clade, which are characterized by having a cartilage skeleton and living in marine habitats. For their part, manta rays stand out for having a flattened body, with gills on their ventral or lower surface.

3. Teleost fish: fish with bones

Teleost fish are characterized by having a bone skeleton, with a vertebral column and a skull. Approximately 30,000 species have been described, the largest variety of known vertebrates. The skin of most of these fish has scales. Gas exchange takes place through the gills.

4. Urodela: salamandras

Salamanders are amphibians that belong to the order Urodela, live in aquatic or terrestrial environments and are characterized by having a tail and four legs.

5. Anura: toads and frogs

Frogs are amphibians that belong to the order Anura. Many species of frogs and toads produce chemicals in their skin glands to defend themselves against predators. Fertilization is external and they undergo metamorphosis in their life cycle.

6. Crocodilia: lizards and crocodiles

The clade Crocodilia belongs to the class Reptilia , four-part vertebrate animals whose eggs have an additional membrane, which allowed them to be laid on the ground. Crocodiles are large reptiles, with flattened snouts and tails compressed on the sides, with eyes and nostrils on the top of the head.

7. Distress: serpientes

The snakes belong to the Squamata clade of the Reptilia class and are characterized by having elongated bodies without limbs, carnivores, they can be poisonous, with a fairly flexible skull. Bothrops jararaca snake venom is used medicinally.

8. Testudines: turtles

Turtles are members of the clade Testudines, which means “to have a shell.” The shell can be made of cartilage or bone. Like the other reptiles, they are ectotherms, their source of body heat is external. They lay eggs on land but live in aquatic environments.

9. Vertebrates with feathers: birds

Birds are vertebrate animals that are characterized by having feathers, which serve as thermal insulators and an aerodynamic surface for flight. They lay eggs and are endothermic, that is, they regulate their internal body temperature.

10. Aquatic mammals: dolphins

Mammals (class Mammalia) are vertebrate animals characterized in that their offspring grow in the embryonic and fetal phase within the mother’s body, and are then suckled with milk. Its body is covered in hair (except for dolphins and whales). They are endothermic like birds.

You may be interested in seeing the branches of biology .

Also know the difference between viviparous, oviparous and ovoviviparous animals .

What are invertebrate animals?

Invertebrate animals are all those multicellular organisms that belong to the Animalia kingdom that do not have a backbone. They do not photosynthesize, so they depend on other organisms (plants and animals) for energy.

Characteristics of invertebrate animals

  • They are a group of immense diversity.
  • They can be fed by filtration of microparticles (such as sponges), by mastication of macroparticles (such as cephalopods) or through fluids (such as endoparasites).
  • The digestion is intracellular largely invertebrates such as poriferas, the cnidarians and flatworms.
  • The digestive system can be as primitive as it is more specialized.
  • The circulatory system can be open, with a large blood reservoir (as in arthropods and mollusks) and a closed system, with arteries and veins, as in worms. Circulation can be by diffusion.
  • They are ectothermic , that is, their heat source is external.
  • Some invertebrates have an exoskeleton , a rigid covering that limits growth, as in insects.
  • Reproduction can be asexual, as in hydras, or sexual as in nematodes and insects.
  • The fertilization is most external in echinoderms, bivalves and polychaetes, while there flatworms and mollusks internal fertilization.
  • The hermaphroditism is a widely distributed among invertebrates like flatworms, sponges, annelids oligochaetes and character.
  • You have different forms of locomotion : aquatic (mollusks), aerial (insects) or terrestrial (worms). The exception is the poriferous in adult stage, they remain immobile in their anchorage site.

You may be interested in seeing the Classification of living beings .

Examples of 10 invertebrate animals

1. Simple invertebrate animals: sea sponges

Marine sponges belong to the phylum Porifera and are the simplest aquatic invertebrate animals. Your body is made up of pores that act like filters. Aplisinia fistularis (yellow sponge), Niphates digitalis (purple sponge), Spiratrela coccinea (red sponge) and Callyspongia sp. (gray sponge) are examples of marine invertebrate biodiversity.

2. Marine invertebrate animals: sea anemones

Sea anemones belong to the Anthozoa class of the phylum Cnidaria. They are characterized by being cylindrical and brightly colored. Anemones live attached to a substrate on the seabed.

3. Flatworms: flatworms

The phylum Platyhelminthes have a flattened body and bilateral symmetry. Within this group are the human parasites Taenia saginata and Schistosoma mansoni .

4. Medicinal invertebrate animals: leeches

The phylum Annelida is characterized by presenting the body in segments. Leeches belong to the Hirudinae class, and are characterized by having sucking organs on their posterior and anterior exteriors. Hirudo medicinalis leeches have long been used for medicinal purposes.

5. Gastropods: snails

A large number of animals are grouped in the phylum Mollusca, including the gastropod class that includes snails. A distinctive feature is that these animals carry a shell. Some cultures appreciate snails in their gastronomy.

6. Insects: flying invertebrates

The phylum Arthropoda is one of the most numerous groups of invertebrates, representing 85% of the animals on Earth. Its name means “jointed feet” and here are the insects, crustaceans, spiders and scorpions.

The insects are concentrated in the subphylum Hexapoda, which is characterized by having a head with sensory antennae, a pair of compound eyes, a thorax with three pairs of legs, and two pairs of membranous wings.

7. Echinoderms: starfish

The phylum Echinodermata with pentaradial symmetry and a calcareous endoskeleton, with characteristic spines on the surface. Starfish are invertebrate creatures that live in the sea.

8. Urochordata: the tunicates

Within the phylum Chordata, where the subphylum Vertebrata is found, there are two subphyla of invertebrate animals: Urochordata and Cephalochordata. The members of Urochordata are known as tunicates, which are characterized by having a larval stage with notochord and nerve cord, which disappear in the adult stage.

9. Cephalopods: octopuses

The class of cephalopods belongs to mollusks, they have a well-developed nervous system, The means of locomotion in water is through the tentacles, which have suckers. They reproduce sexually and defend themselves by throwing dark ink to confuse their predator. The octopus is considered a highly intelligent invertebrate animal.

10. Arachnid arthropods: spiders

Arachnids are a group of arthropods that include spiders, ticks, and scorpions. Spiders are characterized by building a network where their victims are prey. They have two segments: the cephalothorax and the abdomen, and four pairs of legs emerging from the first segment.

You may be interested in knowing the difference between flora and fauna .

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