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In biology, embryonic development is divided into two types based on the complexity of the animals and can be referred to as deuterostomes and protostomes, depending on the species. One of the most noticeable differences between the two types of development is the development of the blastopore, which is the first opening of the animal’s embryo and is one of the most visible differences. Depending on the species, the opening can be either the mouth, as in the case of protostomes, or anus, as in the case of deuterostomes.
Protostomes
Protostomes are lower invertebrate species in which the formation of the mouth occurs prior to the formation of the anus during embryonic development, as opposed to anus-forming species. These animals have a determined and spiral cleavage, and their coelom is formed as a result of the dividing of the mesoderm. Octopuses, squid, snails, centipedes, millipedes, spiders, butterflies, ants, bees, earthworms, clams, oysters, and other protostomes are examples of animals that are classified as protostomes. In this way, the conversion of the blastopore into the mouth or anus distinguishes protostomes from deuterostomes animals at their most fundamental level of differentiation.
Deuterostomes
Deuterostomes go through a process known as radial cleavage during their development. While the blastula is forming as a result of the cleavage of the embryo, the cell division process is taking place in the radial direction. In this group of animals, the initial cavity created by the blastopore develops into the anus of the organism, which is the final stage of development. In addition, after the formation of the anus, the mouth of the organism in question is formed on the other side of the anus. The following clades of deuterostomes animals can be distinguished based on their structural similarities:
- Echinodermata: It 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: Both terrestrial and marine animals are included in this grouping.Example: frog, tiger, bat, turtle, snake, jawless fish, and so on.
- Cephalochordata: They are small marine organisms with segmented bodies that are found in the ocean.Example is lancelets.
- Urochordata: They are also known as Tunicata, and they are sea animals.Examples are sea squirts, Thaliacea, Ascidians, Larvacea, and so on.
- Vertebrata: It is composed of all animals that are classified as belonging to the subphylum vertebrates.Humans, birds, amphibians, fish, and other animals are examples.
- Hemichordata: Hemichordata is a marine species that can be classified as a sister organism to echinoderms, which are a type of sea slug.Examples are Graptolithina, Acorn worm, Pterobranchia, and so on.
Difference between Protostomes and Deuterostomes:
Protostomes | Deuterostomes |
Eventually, the blastopore develops into a mouth in protostomes. | The blastopores in deuterostomes develop into an anal opening as they grow older. |
It exhibits a distinct cleavage pattern. | It has a cleavage pattern that is indeterminate. |
Essentially, it is made up of a solid ventral cord. | It is made up of a nerve cord that is hollow. |
The gut creates the anus by tunnelling its way into the developing embryo. | The gut forms the mouth by tunneling into the embryo and sucking up nutrients. |
A mouth forms first in protostomes. | An anal opening forma at first in deuterostomes. |
As a result, the difference between protostomes and deuterostomes can be distinguished by the position of their organs in their bodies. A mouth forms when the blastopore transforms into an anus, and another cavity on the opposite side forms when a deuterostome transforms into an anus. In protostomes, on the other hand, the mouth is formed from the blastopore.
Similarities of protostomes and deuterostomes:
The protostomes and deuterostomes are distinguished by the fact that they have bilateral symmetry. As a result, these animals are referred to as bilaterians. Using a single plane that passes through the midline of the animal’s body, it is possible to divide a bilaterally symmetrical animal into two mirror-image halves.
Conclusion:
Deuterostome blastopores develop into a mouth while those in protostomes develop into an anal opening.
In biology, embryonic development is divided into two types based on the complexity of the animals and can be referred to as deuterostomes and protostomes, depending on the species. Depending on the species, the opening can be either the mouth, as in the case of protostomes, or anus, as in the case of deuterostomes.Protostomes are lower invertebrate species in which the formation of the mouth occurs prior to the formation of the anus during embryonic development, as opposed to anus-forming species.Deuterostomes go through a process known as radial cleavage during their development. While the blastula is forming as a result of the cleavage of the embryo, the cell division process is taking place in the radial direction.
