Campanularia

Campanularia is one of the best known of the British "Hydroid Zoophytes." It belongs to the class Hydrozoa, to the sub-class Craspedota, and the order Hydroidea. The animal consists of a delicate branched plant-like body, the end of each branch terminating in a small bud-like expansion or cup; the individual zooids live in these cups (hydrothecae), and are connected by prolongations of the soft tissues passing through the hollows of the stem. The whole body is protected by a chitinous covering, the "perisarc": expansions of this at the free ends of the branches protect the "zooids." The reproductive organs are protected by similar expansions of the perisarc, forming buds known as the gonothecae: in each of these is a central stalk, the gonophore, from which are given off on either side a series of buds which develop into medusae. The development may be abbreviated, and no free medusoid form may exist; or the lateral buds may escape as small free-swimming jelly-fish, which ultimately give rise to the fixed colonial stage. Campanularia is closely allied to Sertularia (q.v.), but it differs in that its hydrothecae are borne upon long stalks, which are marked by series of rings.