Differences Between Protostomes and Deuterostomes

Metazoan is a group of animals that have various cells for specific organs and tissues. Also, these animals have a digestive cavity line that is created with specially designed cells. These metazoans can be categorised into two types on the basis of their embryonic development – deuterostome and protostomes. 


The embryonic development of deuterostomes goes through radial cleavage. While the blastula is forming via cleavage of the embryo, the cell division process occurs in radial. In this group of animals, the initial cavity created by the blastopore matures as anus of the organism. Also, the mouth of the concerned organism is created on the other side after the formation of the anus. 

Based on the similarities of structure, the following clades of deuterostomia animals are available-

  • Echinodermata

Echinodermata is exclusively identified as marine animals. The adult echinoderms are recognisable by the radial symmetry.

Example: Sea cucumbers, Starfish, Sand dollars, Sea lilies, etc.

  • Chordates

Chordates include both terrestrial and marine animals.

Example: Frog, Tiger, Bat, Turtle, Snake, Jawless fish, etc.

  • Cephalochordata

Cephalochordata are small marine organisms with a segmented body.

Example: Lancelets.

  • Urochordata

Urochordata is also sea animals and known as Tunicata.

Example: Sea squirts, Thaliacea, Ascidians, Larvacea, etc.

  • Vertebrata

Vertebrata includes all animals that fall under subphylum vertebrate. 

Example: Human, Birds, Amphibians, Fishes, etc.

  • Hemichordata

Hemichordata is a marine species and can be grouped as sister organisms of echinoderms.

Example: Graptolithina, Acorn worm, Pterobranchia, etc.


Protostomes include the lower invertebrate species in which the formation of mouth happens before the creation of anus during embryo development. These animals have determinate and spiral cleavage and through the dividing of mesoderm their coelom forms.

Some examples of protostome are octopus, squid, snail, centipedes, millipedes, spiders, butterflies, ants, bees, earthworms, clams, oysters, etc.

Thus, the fundamental difference between protostomia and deuterostomia animals is the conversion of blastopore into the mouth or anus.

Differences Between Protostomes and Deuterostomes



In deuterostomes, an anus develops from the blastopore.

In protostomes, a mouth develops from the blastopore.

Their coelom is developed from the longitudinal pouches of the archenteron. Hence, they are known as enterocoelous.

Their coelom is developed by dividing the embryonic mesoderm. So, they are known as schizocoelomates.

The gastrointestinal tract is channelled into the embryo and develops the mouth.

The anus forms as the gastrointestinal tract is channelled into the embryo.

Their archenteron development occurs during the initials stage of embryo creation.

They don’t have archenteron development.

By nature, these animals are enterocoelous.

By nature, protostomes can be priapulids.

Deuterostomes’ nervous system consists of hollow nerve fibres and gill slits.

Their nervous system consists of ventral and solid nerve cords.

These animals have evolved more, and their body compositions are complex.

These animals have evolved less, and their body compositions are simple.

Their cell ciliation process is based on a single cell.

Multiple cells are involved in their cell ciliation process.

Deuterostomes are divided into Echinodermata, Chordates, Urochordata, Cephalochordata, Vertebrata, and Hemichordata.

Protostomes include the remaining bilaterian species.

Deuterostomes include a significantly smaller number of species.

Most bilaterian phyla come under protostomes.

An anal opening forms at first.

A mouth forms at first.

These animals have indeterminate cleavage.

They have determinate cleavage.

The cleavage is radial.

The cleavage is a spiral structure.

Complex and higher organisms like human, other terrestrial animals like tiger, monkey, etc. are examples of deuterostomes.

Simpler and lower organisms like Arthropods, Flatworms, Annelids, etc. are examples of protostomes.

Thus, the difference between protostomes and deuterostomes lies in the position of their organs. In deuterostomes, the blastopore transforms into an anus, and another cavity on the opposite side creates a mouth. However, in protostomes, the mouth is created from the blastopore.

To learn about the difference between protostomes and deuterostomes in-depth, go through the study materials available in Vedantu’s website. For quick learning, download our Vedantu app.

FAQ (Frequently Asked Questions)

1. Are Human Deuterostomes?

Ans. Yes, human are deuterostomes.

2. What is the Definition of Deuterostome Definition?

Ans. During the embryonic development of metazoans, if the blastopore turns into the anus, the animals are called deuterostomes.

3. What is Protostome?

Ans. In the time of embryonic development, if the primary cavity turns into a mouth, the animals are called protostomes.