Aequorea Victoria Class: Hydrozoa, Hydroidolina Order: Leptomedusae Family: Aequoreidae Crystal Jelly

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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).

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. The zooplankton (Purcell 1991). Their feeding sessile, polypoid colony is delicate and plant- response is mostly tactile (Hyman 1940) (i.e. like. Medusae develop asexually from buds they use their tentacles to capture prey, on the colony and become free swimming. All Purcell et al. 1987). Additionally, they can medusae from a single colony are the same sense water-born chemicals produced by sex (diecious). Eggs are transparent and crustacean prey, Artemia (Arai 1991), though 100µm diameter (Mills and Strathmann 1987) further research is required to fully and medusae spawn within several hours of understand this behavior. daybreak or sundown (Mills and Strathmann Predators: Aequorea victoria is well 1987). Embryos become planula larvae, protected by nematocysts (stinging cells). which settle and develop into new polypoids. Giant sunfish (Mola mola) eat them, as do The first hydranth forms about a week after some nudibranchs and the hydromedusae settlement, and additional hydranths grow Stomotoca atra (Arai and Jacobs 1980) and from unbranched stolons (Mills and Phacellophora camtschatica (Towanda and Strathmann 1987). Thuesen 2006). Larva: Embryos become tiny planula larvae. Behavior: The small polypoid stage requires Planulae are uniformly ciliated and usually a well-sheltered place in order to attach. The oval or club-shaped. These larvae are non- floating medusa is the stage most commonly feeding and free-swimming. They are armed seen (Figs. 1, 2), but often exhibits high with nematocytes, but lack an apical ciliary mortality after a storm or a sudden pulse of tuft and septa (see Fig. 3, Sadro 2001). fresh water (MacGinitie and MacGinitie 1949). These larvae settle on their sides (Fig. 3) and Aequorea victoria medusae are luminescent become new polyps (Figs. 4, 5) (Strong when stimulated, and provided the original 1925). In culture, the larvae form within 24 source for the commonly-used green hours of fertilization and settle within 3–12 fluorescent protein (GFP) and the days (Mills and Strathmann 1987). luminescent protein aequorin (Mills et al. Juvenile: Juveniles are free, spherical 2007). medusae. They have two tentacles and

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] Bibliography Hydrozoa: polyps, hydromedusae, and siphonophora, p. 118-167. In: The 1. ARAI, M. N. 1991. Attraction of Aurelia Light and Smith manual: intertidal and Aequorea to prey. Hydrobiologia. invertebrates from central California to 216:363-366. Oregon. J. T. Carlton (ed.). University 2. ARAI, M. N., and A. BRINCKMANN- of California Press, Berkeley. VOSS. 1980. Hydromedusae of British 12. MILLS, C. E., and M. F. Columbia and Puget Sound. Canadian STRATHMAN. 1987. Phylum Cnidaria, Bulletin of Fisheries and Aquatic Class Hydrozoa, p. 44-71. In: Sciences. 204:1-192. Reproduction and development of 3. ARAI, M. N., and J. R. JACOBS. 1980. marine invertebrates of the northern Interspecific predation of common Pacific coast: data and methods for Strait of Georgia planktonic the study of eggs, embryos, and coelenterates: laboratory evidence. larvae. M. F. Strathman (ed.). Canadian Journal of Fisheries and University of Washington Press, Aquatic Sciences. 37:120-123. Seattle, WA. 4. BOONSTRA, J. L., M. E. KONEVAL, 13. MURBACH, L., and G. SHEARER. J. D. CLARK, M. SCHICK, M. SMITH, 1902. Preliminary report on a and A. L. STARK. 2015. Milbemycin collection of medusae from the coast oxime (interceptor) treatment of of British Columbia and Alaska. amphipod parasites (Hyperiidae) from Annals of Natural History. 7:pp. 71-73. several host jellyfish species. Journal 14. PURCELL, J. E. 1989. Predation on of Zoo and Wildlife Medicine. 46:158- fish larvae and eggs by the 160. hydromedusa Aequorea victoria at a 5. HYMAN, L. H. 1940. The herring spawning ground in British Invertebrates: Protozoa through Columbia. Canadian Journal of Ctenophora. McGraw-Hill, New York, Fisheries and Aquatic Sciences. London. 46:1415-1427. 6. KOZLOFF, E. N. 1983. Seashore life 15. —. 1991. Predation by Aequorea of the northern Pacific coast. victoria on other species of potentially University of Washington Press, competing pelagic hydrozoans. Marine Seattle. Ecology Progress Series. 72:255-260. 7. —. 1987. Marine invertebrates of the 16. PURCELL, J. E., T. D. SIFERD, and J. Pacific Northwest. University of B. MARLIAVE. 1987. Vulnerability of Washington Press, Seattle. larval herring (Clupea harengus 8. LARSON, R. J. 1986. Seasonal pallasi) to capture by the jellyfish changes in the standing stocks, Aequorea victoria. Marine Biology. growth rates, and production rates of 94:157-162. gelatinous predators in Saanich Inlet, 17. REES, J. T., and C. H. HAND. 1975. British Columbia. Marine Ecology Class Hydrozoa, p. 65-84. In: Light's Progress Series. 33:89-98. manual: intertidal invertebrates of the 9. MACGINITIE, G. E., and N. central California coast. S. F. Light, R. MACGINITIE. 1949. Natural history of I. Smith, and J. T. Carlton (eds.). marine animals. McGraw-Hill Book University of California Press, Co., New York. Berkeley. 10. MILLS, C. E. 2001. Jellyfish blooms: 18. RUSSELL, F. S. 1953. The Medusae are populations increasing globally in of the British Isles. University Press, response to changing ocean Cambridge. conditions? Hydrobiologia. 451:55-68. 19. SADRO, S. 2001. Cnidaria 11. MILLS, C. E., A. C. MARQUES, A. E. (Coelenterata), p. 13-23. In: An MIGOTTO, D. R. CALDER, C. HAND, identification guide to the larval marine J. T. REES, S. H. D. HADDOCK, C. invertebrates of the Pacific Northwest. W. DUNN, and P. R. PUGH. 2007.