Phylum Ctenophora: Ctenophores, commonly known as sea walnuts or comb jellies are exclusively marine, radially symmetrical, diploblastic organisms with tissue level of organisation. Comb jellies are another name for Phylum Ctenophora. The body bears eight external rows of ciliated comb plates, which help in locomotion . Digestion is both extracellular and intracellular. Bioluminescence (the property of a living organism to emit light) is well-marked in ctenophores. Sexes are not separate. Reproduction takes place only by sexual means. Fertilisation is external with indirect development.

Examples: Pleurobrachia and Ctenoplana.

Characteristics of Phylum Ctenophora

• These species are only found in the sea.
• This Phylum’s animals are solitary and free swimming.
• They have a diploblastic acoelomate body structure. The body is translucent, gelatinous, soft, and segmented, with two long, solid, retractile tentacles.
• Body Symmetry: These species have a bi-radial symmetry.
• Tissue: Tissue-level organization is seen in these invertebrates.
• They move by using eight strips of cilia called comb rows. These comb-like rows aid in movement.
• Reproduction happens through sexual methods because they are hermaphrodite animals.
• External fertilization and indirect development are used by these species.
• They have both an external and an intracellular digestive system.
• For balance, they have an aboral sensory organ called the statocyst.
• Respiration and excretion: They lack distinct organs for respiration and excretion, and the body surface is responsible for both.
• Size and shape range from microscopic Phylum Ctenophora spheroids (0.04 inch) to lengthy (4.9 foot) ribbons. Ctenophora are lobe-shaped animals.

Classification of Phylum Ctenophora

Ctenophores are classified into two groups and many orders based on their body shapes and features Ctenophora is split into two groups based on the presence or lack of tentacles.

• Class-1 Tentaculate is a class of organisms that have tentacles.
• Class-2 Nuda means without tentacles.

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By Team Learning Mantras