Knowra Siphonophore Siphonophore A siphonophore is a marine hydrozoan colony of specialized, interconnected zooids. The zooids perform different functions while remaining physiologically integrated as one organism.
Zooid : A specialized individual body unit in a colonial animal, often adapted for a particular function. Each siphonophore is assembled from zooids that specialize in feeding, reproduction, movement, or defense.
Pneumatophore : A gas-filled float found in some siphonophores, helping keep the colony near the ocean surface. In surface-dwelling siphonophores, this float provides buoyancy for the colony.
Portuguese man o' war : A surface-dwelling siphonophore with a gas-filled float and long stinging tentacles. Its conspicuous float and specialized zooids make colonial organization visible.
Jellyfish : The common name for medusae, free-swimming gelatinous animals found in several cnidarian groups. Unlike a solitary jellyfish, a siphonophore divides body functions among integrated zooids.
Biological individuality : The problem of defining what counts as an individual organism in biology. A siphonophore’s many specialized zooids challenge simple boundaries between individual and colony.
Hydrozoa : A class of cnidarians that includes hydroids, fire corals, and many colonial forms. Siphonophores are hydrozoans, sharing the group’s cnidarian body plan and life-history traits.
Nectophore : A swimming zooid in a siphonophore, often shaped like a bell and powered by jet propulsion. Nectophores contract in coordinated sequence to propel the colony through water.
Praya dubia : A deep-sea siphonophore known for its exceptionally long, chainlike colony. This species illustrates how a colony can extend into a long, coordinated hunting structure.
Coral : A cnidarian, usually colonial, whose polyps build or inhabit a supporting structure. Corals are also colonies, but their polyps generally lack siphonophore-style division into swimming and feeding zooids.
Coloniality : The biological condition of living as a colony of connected or associated units. Siphonophores offer a striking case for studying how colonies become integrated organisms.
Show all 25