View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by University of Oregon Scholars' Bank Phylum: Cnidaria Aequorea victoria Class: Hydrozoa, Hydroidolina Order: Leptomedusae Family: Aequoreidae Crystal Jelly Taxonomy: Originally described as Bell: The bell is large and relatively Mesonema victoria (Murbach and Shearer, flat, and contracts when swimming. 1902), current synonyms and previous names It is thick, gelatinous, and rigid, with a ring for Aequorea victoria include Aequorea canal around the margin and radial canals aequorea, A. forskalea, and Campanulina running from the mouth to the margin (Fig. 1). membranosa (a name proposed for the polyp It has a short, thick peduncle (Arai and form by Strong 1925) (Mills et al. 2007; Brinckmann-Voss 1980). Schuchert 2015). The taxonomy of Radial Canals: Aequorea Aequoreidae is currently in flux and awaiting victoria individuals can have over 100 further molecular research (Mills et al. 2007). symmetrical, unbranched radial canals. In mature specimens all radial canals reach the Description bell margin (Mills et al. 2007, Kozloff 1987) General Morphology: Aequorea victoria has (Figs. 1, 2). Excretory pores open at the two forms. Its sexual morphology is a canal bases near the tentacles (Hyman gelatinous hydromedusa. It has a wide bell, 1940). many tentacles, and radial canals that run Ring Canals: The ring canal from the mouth to the bell margin, where they surrounds the bell margin. are connected by a ring canal. Suspended Mouth: The mouth is part of from the inside of the bell by a peduncle is the the tubular manubrium, which is large and manubrium, or mouth. A velum rings the surrounded by numerous frilled lips (Fig. 2). inside of the bell margin (Fig. 1). Its asexual Tentacles: The tentacles are morphology is a small polyp. Each polyp has hollow, unbranched, and numerous (up to a stem (hydrocaulus), and most have a 150, often about as many as radial canals) sheathed (thecate) hydranth with a mouth (Arai and Brinckmann-Voss 1980, Mills et al. (manubrium), stomach, tentacles, and an 2007). They occur on a single whorl on the operculum (Fig. 4). Rather than having ring canal (Mills et al. 2007). Not all of the hydranths, some polyps have gonophores tentacles are the same length and they can (Fig. 5). be very long when extended (Kozloff 1987). They have stinging cells (nematocysts) used Medusa: in prey capture and defense. According to Size: Aequorea victoria is much wider Purcell (1989) these nematocysts are isorhiza than tall and can get up to 12 cm in diameter and microbasic mastigophore, but there is (Kozloff 1987), but only 4 cm in height (Arai variation in cnidoblast naming schemes and Brinckmann-Voss 1980). between researchers. Color: Adult specimens are Velum: The velum is a flap of transparent aqua blue with whitish radial tissue, barely visible inside the bell rim, which canals, while juveniles have a green sub- is used for swimming (Fig. 1) (Hyman 1940). umbrella, opalescent gray or milky gonads, Gonads: Gonads in A. victoria are and occasionally have brown tentacle bulbs not finger-like as in many other (Arai and Brinckmann-Voss 1980). Mature hydromedusae. They develop once the bell specimens also fluoresce and luminesce, with diameter reaches 25 mm (Mills and their luminescence concentrated around the Strathmann 1987), and are suspended from bell margin (Kozloff 1983). and span nearly the entire length of the radial Body: canals (Fig. 1) (Mills et al. 2007, Kozloff 1987). Piazzola, C.D. 2015. Aequorea victoria. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12624 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Sensory: Aequorea victoria lacks eyespots further offshore than A. victoria (Mills et al. but has statocysts, which are used for 2007). balance and orientation in the water column Aequorea victoria medusae are very (Kozloff 1983). large among hydrozoans, and this species is Polyp: Rare (Mills 2001). the only Leptomedusa with more than 24 Size: Very small (0.5-1 mm) (Figs. 3– radial canals (most have only four) (Rees and 5) and composed of simple or slightly Hand 1975). The Scyphozoa, or true jellyfish, branched colonies with rarely more than two are large, have fringed mouth lobes, polyps (Strong 1925). scalloped margins, no velum, and a complex Color: pattern of radial canals (Rees and Hand Body: 1975). Some scyphozoans also have Pedicel: The polyp is prominent, pendant oral arms. Very young A. pedicellate (Kozloff 1987; Mills et al. 2007), victoria, up to 4 mm in diameter, can look with hydrocaulus (stem) up to 2.5 mm in similar to Polyorchis penicillatus in shape (Fig. length, and is ringed rather than spirally 6); additionally, the young A. victoria lack the grooved (Mills et al. 2007). many radial canals that they will develop as Hydranth: Each polyp has they mature, and so seem more similar to the about twenty tentacles, a mouth, and an P. penicillatus with its four radial canals intertentacular web armed with nematocysts. (Russell 1953). The colonies are stolonal (connected by horizontal shoots at the base of each Ecological Information hydrocaulus) (Mills et al. 2007). The hydranth Range: Type localities are Victoria Harbor, is covered by a theca (hydrothecae) that is British Columbia and Puget Sound, deeper than it is wide and is able to hold the Washington (Murbach and Shearer 1902). entire hydranth when contracted (Mills et al. Found in temperate waters in both northern 2007; Kozloff 1987) and the hydrothecae are and southern hemispheres. Well known in radially symmetrical and do not have true Puget Sound and British Columbia. marginal cups (Mills et al. 2007). Instead, they Local Distribution: Oregon distribution have longitudinal striations with straight walls includes most bays and nearshore waters. (Mills et al. 2007; Kozloff 1987), and the Habitat: Medusae are found in plankton and opercular valves are continuations of the harbors (e.g., Charleston boat basin). The hydrothecal margin (Mills et al. 2007; Kozloff attached, or polyp, forms have been found 1987). intertidally (Mills et al. 2007). Gonangium: Some branches Salinity: Collected at salinities of 30 and of a colony have gonophores (Fig. 5) that cannot tolerate large fresh water influx (e.g., reproduce by releasing free, spherical from storms, MacGinitie and MacGinitie medusae (Mills et al. 2007; Kozloff 1987). 1949). Cnidae: The intertentacular web Temperature: A cold to temperate species. contains nematocysts (Mills et al. 2007). Tidal Level: Medusae are pelagic, while polyps are intertidal. Possible Misidentifications Associates: The small anemone, Peachia The family Aequoreidae includes quinquecapitata, is sometimes parasitic on A. leptomedusae with numerous radial canals, victoria individuals (Puget Sound, gonads attached to the radial canals, a broad Washington). Aequorea victoria ingests P. short stomach, but lacking marginal or lateral quinquecapitata larvae, and once inside the cirri (Arai and Brinckmann-Voss 1980). There hydromedusae, the larvae feed on nutrients in is only one other Aequorea species locally: A. the radial canals and gonads. These parasitic coerulescens. It is larger than A. victoria and larvae grow and metamorphose into juveniles having a bell that is up to 25 cm in width with while still inside A. victoria. Ultimately, the three to six times as many tentacles as radial juvenile leaves its host mid-water and may canals. It is also less common and lives Piazzola, C.D. 2015. Aequorea victoria. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. become ectoparasitic on another A. victoria scattered exumbrellar nematocysts that form host (Mills and Strathmann 1987). a broad ring on the lower half of the bell (Fig. The hydromedusae are also parasitized by 6) (Mills et al. 2007 and Kozloff 1987). They larval and juvenile forms of Hyperia are not considered mature until they reach medusarum. Aequorea victoria provides a about 50 mm in diameter (Mills and pelagic host on which hyperiid amphipods can Strathmann 1987). Juvenile recruitment overwinter (Boonstra et al. 2015, Towanda occurs in the spring (Larson 1986). and Thuesen 2006). Longevity: Unknown. Abundance: Aequorea victoria is one of the Growth Rate: Medusae grow very quickly, most common large medusae. At the right especially as compared to anthozoans time of year, it can occur in great numbers (MacGinitie and MacGinitie 1949). In locally. It was present in high densities in laboratory conditions they grow from egg to Puget Sound, Washington, from the early polyp in less than six days (Strong 1925). 1960s to the mid-1990s. At that time, Food: Their diet consists predominately of thousands were collected by researchers for soft-bodied prey (e.g. ctenophores, medusae, their aequorin (luminescent protein) and GFP cannery refuse), but they also eat mature (Green Fluorescent Protein). Since the mid- crustaceans, crustacean larvae (Purcell 1990s, A. victoria populations have 1989), and polychaetes. They are an decreased in both number and size, though important predator of fish larvae and eggs this trend may be due to environmental (Purcell 1989), but once the fish larvae pass change as well as high takes (Friday Harbor) the post-yolksac stage they are better able to (Mills 2001). escape the medusae and are less commonly preyed upon (Purcell et al. 1987). They also Life-History Information participate in intraguild predation, eating other Reproduction: Hydrozoans provide a good gelatinous species that compete for example of alternation of generations.