Order Lobata:

Ctenophores in order Lobata have thick, paired lobes.Mnemiopsis leidyiAlso known as the sea walnut, Mnemiopsis leidyi have a lobed, oval-shaped and transparent body. They are originally native to the shallow coastal waters of the Western Atlantic ocean. However, they have been introduced as an invasive species to the Black Sea. They eat the eggs and larvae of pelagic fish, causing a decline in fish populations, especially the commercially important hamsa anchovy. Biologists successfully to control the M. Leidyi populations using another ctenophore, B. ovata. In addition to being preyed upon by B. ovata, M. Leidyi can be preyed upon by birds, fish, and jellyfish. They are also hermaphroditic and conduct external fertilization.

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