Semaeostomeae

invertebrate order

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Last updated

July 13, 2026

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The Semaeostomeae are an order of jellyfish belonging to the class Scyphozoa. These invertebrates are characterized by their large mouths, which have four lips, and by the presence of large tentacles around the margin of their umbrella-shaped bodies.12

Jellyfish, including those in the Semaeostomeae order, are primarily composed of water, with their bodies consisting of two cellular layers surrounding a thick, gelatinous mesoglea. They typically have a life cycle that includes a sessile polyp stage, from which young medusae bud off and mature into adults. The Semaeostomeae order includes about 50 species, many of which are found in coastal waters and have wide geographic distributions. Common examples include moon jellies (Aurelia) and sea nettles (Chrysaora).2

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cnidarian
Annotated classification
Order Semaeostomeae Most common and best known jellyfishes. Full alternation of polyp and medusa stages. Bell domed or flattened, with the margin scalloped into 8 or more sections. Edges of single mouth drawn out into 4 long arms. Most species in warm, coastal waters, a few…
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Order Semaeostomeae Most common and best known jellyfishes. Full alternation of polyp and medusa stages. Bell domed or flattened, with the margin scalloped into 8 or more sections. Edges of single mouth drawn out into 4 long arms. Most species in warm, coastal waters, a few…
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jellyfish
…life cycle characterizes the order Semaeostomeae, which contains some 50 species of mainly coastal-water jellyfish, several of which have very wide geographic ranges. Included among these are members of the genera Aurelia and Chrysaora and the big red jellyfish, Tiburonia granrojo (subfamily Tiburoniinae), one of only three species of
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…life cycle characterizes the order Semaeostomeae, which contains some 50 species of mainly coastal-water jellyfish, several of which have very wide geographic ranges. Included among these are members of the genera Aurelia and Chrysaora and the big red jellyfish, Tiburonia granrojo (subfamily Tiburoniinae), one of only three species of
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