Warty Comb Jelly (Mnemiopsis Leidyi)

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The warty comb jelly or sea walnut (Mnemiopsis leidyi) is a species of comb jelly, originally native to the western Atlantic coastal waters.

Kingdom: Animalia
Phylum: Ctenophora
Class: Tentaculata
Order: Lobata
Family: Bolinopsidae
Genus: Mnemiopsis
Species: M. leidyi

  • The body of a warty comb jelly is lobed, oval-shaped and transparent.
  • Fours rows of ciliated combs run vertically along the body and glow blue-green when disturbed.
  • They have several feeding tentacles and do not sting.
  • Their body is 97% water.
  • Maximum body length of 7-12 cm and a diameter of 2.5 cm.

  • Temperate to suptropical estuaries along the Atlantic coast of North and South America

  • They are carnivores that consume zooplankton, other comb jellies, and eggs and larvae of fish.
  • Sometimes eats smaller individuals of its own kind.

  • They are hermaphrodite, meaning they have reproductive organs associated with both male and female.
  • Self fertilization
  • Eggs and sperm are released into water where external fertilization occurs.

Invasive Species: The Warty Comb Jelly was introduced as an invasive species in a variety of locations.
1980s - Black Sea:
  • Most likely introduced through a merchant ship
  • By 1989 there were about 400 of them per cubic meter of water
  • Caused dramatic drops in fish populations by competing for food and eating the young and eggs
1999 - Caspian Sea:
  • 75% of zooplankton in the Caspian Sea was depleted
  • Affected the whole food chain
2006 - North and Baltic Seas
  • Has been spreading throughout the Mediterranean basin since it was first introduced