Ctenophores: What are, characteristics and examples

The ctenophores, popularly known as combs combare Marine animals which are characterized by their gelatinous body and its planktonic nature. Its name, which comes from the Greek and means “comb carrier”, is due to the eight rows of cilia they own, which they use to move in the water.

He Filo Ctenophora includes More than 200 speciesand they are in All oceans of the planet, representing a significant part of the Planktonic biomass. Its size varies considerably, from small species of less than one centimeter to others that can reach lengths of up to two meters. Despite its low fossil representation, copies have been found in ancient geological formations that present similarities with modern ctenophores, which suggests a long evolutionary history.

In this link you can learn more about what zooplankton is.

• Diploblastic structure: They have two embryonic layers: ectoderm and endoderm, with a little differentiated mesoglea between them.
• Accelerated: They have no body cavity.
• Radial symmetry: Its body structure is radially symmetrical, allowing divisions along multiple planes.
• Tissue organization: They have a tissue level of organization, with different types of specialized cells.
• Locomotion organs: They use eight rows of numb combat plates, which are the organs responsible for their locomotion.
• Variable size: They can measure between 1 mm and 1.5 m, showing considerable diversity in size.
• Dam capture: They have coloblasts in their tentacles, which are similar to the cnidoblasts of the cnidarians, but without efficient cells.
• Sensitive cells: The external epidermis contains cells that secrete mucus and have protective functions.
• Simple nervous system: They lack brain and central nervous system, but have a nervous network around the oral region.
• Internal cavity: Its cavity includes the mouth, the pharynx and internal ducts, covered by the gastrodermis.
• Bioluminescence: They are able to emit light, creating visual effects in water. Here you can learn more about what bioluminescence and examples are.
• Regeneration: They have the ability to regenerate damaged tissues.

All species of ctenophores are Carnivorousand feed on:

• Rotifers and small crustaceanssuch as copepods, amphipods and eupháusids.
• Planktonic larvae of various species, including molluscs and snails.
• Some, like Beroideos, feed on Other ctenophores.

They use several methods of capturing their prey to feed, such as:

• The dams are captured using long tentacles or by one mucous layer In the body.
• The coloblasts In the tentacles they help in the capture of dams.
• The species of the genus Haeckelia use Nematocistos obtained from its cnidaria prey.
• Some species, such as euplokamis, have Prénsiles side branches in their tentacles that catch the dams.

There is a classification in which there are two main classes of ctenophores according to their diet:

• Tentaculata: Sea nuts have a large mouth and feed mainly with larval and copepod mollusks.
• NUDA: These species lack tentacles and have a large mouth. They feed on jellyfish and other ctenophores.

The reproduction of jellyfish combs unique characteristics, standing out for their Biphasic sexual reproduction. This initial phase, known as larval reproduction or dysogleit has been observed in various species of ctenophores, including tentaculated and lobed cylures. However, recent investigations have shown that Ctenophore MNEMIOPSIS LEIDYI It has no separate phases of early and adult reproduction. Instead, it begins to reproduce to a small body size and display continuously under favorable environmental conditions.

Most ctenophores are Simultaneous hermaphroditesalthough they exist Some dioic species. In addition, some members of the Plattycan order can reproduce asexually due to fragmentation. In this link you can read about hermaphrodite animals: reproduction and examples.

Reproductive tissues are developed in southern gastrovascular channels, and gametes are expelled by the mouth; Fertilization generally occurs external form, in water. The production of gametes is usually daily, but it can decrease if there is food shortage. In terms of parental investment, ctenophores do not exhibit parental participation beyond the production of gametes. Here you can learn about external fertilization: what is and animals.

Tentaculata class

• AULACOCTENA ACUMINATE
• Callianira Antarctica
• Pleurobrachia bachei
• EUPLOKAMIS CRINITE
• Bathocyroe Fosteri
• Ocyropsis Fusca
• Lesueuria Hyboptera
• Bolinopsis microptera
• Cruentiventer lampocteis
• Cestum Veneris
• Velamén parallel
• Coellopana Fishelsoni
• Multiformis Vallicula
• Lyrocteis flavopallidus
• Neritica Ctenoplana
• Thalassocalyce Unconsons

NUDA class

• Beroe
• Neis

• Ciliary plates: Ctenophores have radially arranged ciliary plates to swim; Cnidarians do not have this characteristic.
• Tentacle location: In the ctenophores, the tentacles are found in the abort pole, while in the cnidarians they are around the mouth.
• Specialized cells: The ctenophores have coloblasts for the capture of dams, while the CNIDARIES have nematocystos.
• Segmentation: segmentation in ctenophores is determined; In Cnidarians, it is undetermined.
• Larva type: The larva of the ctenophores is cidypid, while the Larva Flanula is practically absent in this group.
• Life cycle: The CNIDARIES have alternation of phases between polyp and jellyfish, which does not happen in the ctenophores.
• Sensory organ: The combat jellyfish have a statocyst, while the Cnidarians do not have this organ.
• Origin of muscle cells: In ctenophores, muscle cells originate in the mesoglea; In the cnidarians, they develop in the epidermis or gastrodermis.

In this other article you can learn more about the Cnidarians: characteristics and examples.

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