#scyphozoa

[snototter]

A pink lions mane jellyfish (Cyanea capillata) in the White Sea

by Alexander Semenov

[bestanimal]

Round 3 - Scyphozoa - Semaeostomeae

(Sources - 1, 2, 3, 4)

Order: Semaeostomeae

Common Name: “flag-mouth jellies”

Families: 5 - Cyaneidae, Drymonematidae (“pink meanies”), Pelagiidae, Phacellophoridae (“egg-yolk jellies”), and Ulmaridae

Anatomy: characterized by four long, frilly oral arms surrounding a quadrate mouth; tentacles line the domed bell; gastrovascular system consists of four unbranched pouches radiating outwards from the central stomach

Diet: zooplankton, crustaceans, and fish

Habitat: oceans worldwide; some species may enter brackish or even fresh water

Evolved in: Cambrian

Do you have a favorite in Semaeostomeae?

One or more of my favorite animals is in Semaeostomeae

I love at least one or more of these animals

I like at least one or more of these animals

I am neutral about at least one or more of these animals

I dislike all of these animals

Voting ended onNov 15, 2025

Propaganda under the cut:

The Lion’s Mane Jelly (Cyanea capillata) (image 3) is one of the largest jellyfish, with the largest recorded specimen having a bell width of 210 cm (7 ft) and tentacles around 36.6 m (120 ft) long.

While most jellies are exclusively marine, the Bay Nettle (Chrysaora chesapeakei) ventures into the Chesapeake Bay’s brackish water all the way up into the freshwater of Baltimore’s Inner Harbor.

The Giant Phantom Jelly (Stygiomedusa gigantea) (image 4) is a deep sea jellyfish that is rarely seen, with only around 110 sightings in 110 years. It thought to be one of the largest invertebrate predators of the ocean's midnight zone and twilight zone, with an umbrella-shaped bell that can grow up to 1 m (3.3 ft) in diameter and paddle-like arms that can grow up to 10 m (33 ft) in length. The bell's pliant tissue allows for the jellyfish to stretch 4 to 5 times its size, presumably to engulf their prey. They do not have any stinging tentacles and instead use their arms to trap and engulf their prey which consists of plankton and small fish. The Giant Phantom Jelly has a symbiotic relationship with the Pelagic Brotula (Thalassobathia pelagica), for which it provides food and shelter beneath its massive billowing bell, while the fish aids the jelly by removing parasites.

The Mauve Stinger (Pelagia noctiluca) is a fairly small purple jellyfish that is able to bioluminesce. Light is emitted in the form of flashes when the medusa is stimulated by turbulence created by waves or by a ship's motion. Unusually among cnidarians, Mauve Stingers are able to consume phytoplankton, alongside copepods and other usual planktonic fare.

The Moon Jelly (Aurelia aurita) (see gif above) is gaining popularity in aquarium touchtanks as they lack long tentacles and their sting has little to no affect on humans. They are also one of the longer-lived jellyfish, living up to two years in their medusa form, and are easy to rear and feed, making them a good candidate for giving humans an up-close learning experience with jellies. Fun fact: my dad let me watch The Sphere (1998) when I was 7 and it gave me Scyphophobia, a fear of jellyfish, that lasted for several years. I knew the behavior of the jellyfish as depicted in the movie wasn’t real, but I still wouldn’t enter the ocean for the next 5 years, and when I did start entering the ocean again every time I saw a jellyfish I would get out and not go back in again for another full year. It took a touch tank and several positive experiences with some Moon Jellies to get over my fear, and now I would say I’m fully recovered!

[saritawolf]

Blue Blubber Jellies (Catostylus mosaicus) - (c) SaritaWolf - please do not repost

[wikipediapictures]

Cephea cephea

“Cauliflower Jellyfish, Cephea cephea at Marsa Shouna, Red Sea, Egypt #SCUBA” - via Wikimedia Commons

[herpsandbirds]

Placental jellyfish

Is it a placenta? Is it a jellyfish? NO! YES!

Deepstaria enigmatica, family Ulmaridae, order Semaeostomeae, class Scyphozoa

Usually found in Antarctic and near-Antarctic seas, but have been found in the Atlantic as far South as the Gulf of Mexico.

Usually found at depths of 600–1,750 m (1,970–5,740 ft).

This species is known to have symbiotic (possibly parasitic) isopods living in their bells.

Find out more:

Solving the Mystery of the Placental Jellyfish | Deep Sea News

Deepstaria enigmatica - Wikipedia

Better and New Video of the Enigmatic Placental Jellyfish | Deep Sea News

[missingnorockl]

I see no difference.

[pers-art]

hey, thanks @chaumas-deactivated20230115 (it's on webtoon!)

inspired by this post

[psappho-loves-staurozoans]

Drew a species of Cnidarian for every class 1. *Chrysaora colorata* 2. *Melithæa ochracea* 3. *Tripedalia cystophora* 4. *Hydra vulgaris* 5. *Aulactinia veratra* 6. *Myxobolus cerebralis* 7. *Polypodium hydriforme* 8. *Calvadosia campanulata*