Zappas jellyfish

Phialella zappai

ORDER Conica

FAMILY Phialellidae

TAXONOMY

Phialella zappai Boero, 1987, Bodega Bay, California, United States.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Hydroid: colony simple, unbranched; hydranth very extensile, with about 14 tentacles, alternately held upward and downward. Oral part of the hydranth is globular, separated from the rest of the body. Hydrotheca cylindrical, elongated, with an operculum of about seven cusps separated from the hydrothe-cal wall by a thin line, not always evident. Diaphragm present. Pedicel is as long as the hydrotheca or a little shorter, annu-lated throughout. Gonothecae on the stolon, arising from short, annulated pedicels, with wavy or smooth walls, tapering below and truncate above, with one or two medusa buds.

Medusa: newly released medusae sub-spherical, about 0.002 in (0.6 mm) in diameter, with four tentacles, four interradial tentacular bulbs deprived of tentacles, and four radial canals with medial darker areas. Eight statocysts, with 1-3 statoliths, are on the inner edge of the ring canal, supported by a cushion of cells. Manubrium is short (one third of the bell cavity), with four short lips. Tentacular nematocysts are in clusters, giving a moniliform appearance to the tentacles. Perradial tentacular bulbs are almost round or triangular, interradial tentacular bulbs much smaller, but evident. The medusae grow rapidly, reaching 0.11 in (3 mm) in diameter in 10 days, dome shaped with four well-developed inter-radial tentacles, and eight developing adradial tentacles. At this age, the eggs are clearly visible. Manubrium cruciform, lips more evident and starting to bend upward. Tentacular bulbs still round, tending to elongate. Tentacles moniliform. Development continues with an increase in size and number of tentacles (36 the highest number observed). Adult specimens dome shaped, with gonads almost in the middle of the radial canals. Manubrium cruciform, with folded lips bending upward, with four gastric pouches; four black spots may be present at its base. Tentacular bulbs triangular, but still rounded. Tentacles evidently moniliform.

DISTRIBUTION

Endemic to the west coast of the United States (California). (Specific distribution map not available.)

HABITAT

The hydroid grows on mussel shells. The medusa is in coastal plankton.

BEHAVIOR Nothing is known.

FEEDING ECOLOGY AND DIET

Under laboratory conditions, both polyps and medusae feed on Artemia nauplii; in the wild they probably feed on small crustaceans.

REPRODUCTIVE BIOLOGY

Each gonotheca produces one or two medusae that, under laboratory conditions, continue to develop also after reaching sexual maturity. Some specimens become mature 10 days after liberation. They can develop a new gonad after the first spawning.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS

This species was named after the modern music composer Frank Zappa (1940-1993), who, in exchange, wrote a song about it ("Lonesome Cowboy Nando"). ♦

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