Range: Tropical and temperate marine waters worldwide Habitat: Continental shelves, bays, estuaries, and deep waters Size: About 1 foot (30.5cm) in diameter; Up to 10 feet (3m) long tentacles Diet: Zooplankton, small fish, squid, copepods, fish eggs, and jellyfish Threats: Fish, jellyfish, nudibranchs, sea turtles, tuna, and ocean sunfish Life span: One year or less

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Today on animal fact files we're talking about sea nettle jellyfish. We won't sting, be sure to subscribe, and thank you to Chin Yiren for today's request. There are approximately fifteen species of sea nettle jellyfish, though, as with any group of animals, this number can fluctuate with new information. The genus name for sea nettle jellyfish is tied to Greek mythology. One of Medusa’s sons, Chrysaor, was adorned in golden armor, and so too are some sea nettle jellyfish. They come in other colors, too. Sea nettle jellyfish may appear ghostly white, others look deep purply, black, but probably the most recognizable are those who come in bright shades of gold.

Sea nettle jellyfish are found throughout the world’s oceans in tropical and temperate waters. They’re usually seen along continental shelves and sometimes occur in large numbers in bays and estuaries, though they can live in deeper water areas, as well, such as with the mysterious black sea nettle jellyfish. Often their place in the water column can depend on food availability and the season.

Sea nettle jellyfish are carnivores and eat anything from zooplankton, small fish, squid, copepods, fish eggs, and even other jellyfish. They use their stinging tentacles to capture and subdue their prey. We’ve talked about this previously in other episodes, but jellyfish sting using nematocysts. In the case of sea nettle jellyfish, the stingers contain a chemical that tempers food items. The food is transported along the sea nettle’s oral arms, which are those big fluffy parts in the middle of the jellyfish, up to the jellyfish’s mouth.

Sea nettle jellyfish usually have four oral arms and can have anywhere from 24 to 40 string-like tentacles along the edges of their bells, which is the dome-shaped part of the jellyfish’s body. Even in individuals of the same species the number of tentacles can vary, so tentacle count isn’t typically used to identify species. Even their size can fluctuate.

In times of plenty, jellyfish may increase in size, and in times of famine, their bodies may shrink. As a loose average, sea nettle jellyfish may be about a foot (30.5 centimeters) across and have ten foot (3 meter) tentacles, but there are much smaller species, like the compass jellyfish, and much larger, like the black sea nettle who can reach three feet (90 centimeters) across its bell and may have up to 20 foot (6 meter) tentacles.

Seasons also play a role in sea nettle populations and where they may be living. Although they are still generally at the whim of tidal and air currents, Sea nettle jellyfish are able to propel themselves through the water. Some species, like the Pacific sea nettles, form blooms in which the adults purposefully stay in a certain area to keep them close to places their young can live successfully.

At certain times of the year, groups of adult sea nettles will come together to breed. Sea nettle jellyfish are broadcast spawners. The female will take in a male’s sperm through her mouth and her fertilized eggs will remain with her. The eggs will hatch into larvae that stay with their mother until they’re ready to sink to the ocean floor. There, they’ll attach and turn into polyps. These polyps produce clones through budding until they metamorphose into adults. This means that sea nettle jellyfish, like other jellyfish, are both sexual and asexual reproducers, and generally this whole process is believed to occur within a year.

Sea nettle jellyfish larvae may be eaten by all kinds of sea life including fish and other jellyfish; polyps are eaten by nudibranchs; and adults are taken by sea turtles, tuna, and ocean sunfish, but their numbers in general may be rising. Scientists believe increases in sea temperature as well as human created runoff may be giving jellyfish the upper hand in the ocean food web.

For more facts on sea nettle jellyfish, check out the links in the description. Give a thumbs up if you learned something new today, and thank you for watching Animal Fact Files.