Aequorea Victoria Class: Hydrozoa, Hydroidolina

Aequorea victoria Class: Hydrozoa, Hydroidolina

Order: Leptothecata Crystal jelly Family: Aequoreidae

Taxonomy: Originally described as Meso- sionally have brown tentacle bulbs (Arai and nema victoria (Murbach and Shearer, 1902), Brinckmann-Voss 1980). Mature specimens current synonyms and previous names for also fluoresce and luminesce, with their lumi- Aequorea victoria include Aequorea ae- nescence concentrated around the bell mar- quorea, A. forskalea, and Campanulina gin (Kozloff 1983). membranosa (a name proposed for the pol- Body: yp form by Strong 1925) (Mills et al. 2007; Bell: The bell is large and relatively Schuchert 2015). The taxonomy of Ae- flat, and contracts when swimming. quoreidae is currently in flux and awaiting It is thick, gelatinous, and rigid, with a ring ca- further molecular research (Mills et al. nal around the margin and radial canals 2007). running from the mouth to the margin (Fig. 1). It has a short, thick peduncle (Arai and Brinck- Description mann-Voss 1980). General Morphology: Aequorea victoria Radial canals: Aequorea victo- has two forms. Its sexual morphology is a ria individuals can have over 100 symmetrical, gelatinous hydromedusa. It has a wide bell, unbranched radial canals. In mature speci- many tentacles, and radial canals that run mens all radial canals reach the bell margin from the mouth to the bell margin, where (Mills et al. 2007, Kozloff 1987) (Figs. 1, 2). they are connected by a ring canal. Sus- Excretory pores open at the canal bases near pended from the inside of the bell by a pe- the tentacles (Hyman 1940). duncle is the manubrium, or mouth. A velum Ring canal: The ring canal sur- rings the inside of the bell margin (Fig. 1). Its rounds the bell margin. asexual morphology is a small polyp. Each Mouth: The mouth is part of the polyp has a stem (hydrocaulus), and most tubular manubrium, which is large and sur- have a sheathed (thecate) hydranth with a rounded by numerous frilled lips (Fig. 2). mouth (manubrium), stomach, tentacles, Tentacles: The tentacles are and an operculum (Fig. 4). Rather than hav- hollow, unbranched, and numerous (up to ing hydranths, some polyps have gono- 150, often about as many as radial canals) phores (Fig. 5). (Arai and Brinckmann-Voss 1980, Mills et al. Medusa: 2007). They occur on a single whorl on the Size: Aequorea victoria is much wider ring canal (Mills et al. 2007). Not all of the than tall and can get up to 12 cm in diameter tentacles are the same length and they can (Kozloff 1987), but only 4 cm in height (Arai be very long when extended (Kozloff 1987). and Brinckmann-Voss 1980). They have stinging cells (nematocysts) used Color: Adult specimens are transpar- in prey capture and defense. According to ent aqua blue with whitish radial canals, Purcell (1989) these nematocysts are isorhiza while juveniles have a green sub-umbrella, and microbasic mastigophore, but there is opalescent gray or milky gonads, and occa- variation in cnidoblast naming schemes be- tween researchers. A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected]

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.

Velum: The velum is a flap of 1987). tissue, barely visible inside the bell rim, Gonangium: Some branches of which is used for swimming (Fig. 1) (Hyman a colony have gonophores (Fig. 5) that repro- 1940). duce by releasing free, spherical medusae Gonads: Gonads in A. victoria are (Mills et al. 2007; Kozloff 1987). not finger-like as in many other hydromedu- Possible Misidentifications sae. They develop once the bell diameter The family Aequoreidae includes lepto- reaches 25 mm (Mills and Strathmann medusae with numerous radial canals, gon- 1987), and are suspended from and span ads attached to the radial canals, a broad nearly the entire length of the radial canals short stomach, but lacking marginal or lateral (Fig. 1) (Mills et al. 2007, Kozloff 1987). cirri (Arai and Brinckmann-Voss 1980). There is only one other Aequorea species locally: A. Sensory: Aequorea victoria lacks eyespots coerulescens. It is larger than A. victoria and but has statocysts, which are used for bal- having a bell that is up to 25 cm in width with ance and orientation in the water column three to six times as many tentacles as radial (Kozloff 1983). Cnidae: The intertentacular canals. It is also less common and lives fur- web contains nematocysts (Mills et al. ther offshore than A. victoria (Mills et al. 2007). 2007). Aequorea victoria medusae are very Polyp: Rare (Mills 2001). large among hydrozoans, and this species is Size: Very small (0.5-1 mm) (Figs. 3– the only Leptomedusa with more than 24 radi- 5) and composed of simple or slightly al canals (most have only four) (Rees and branched colonies with rarely more than two Hand 1975). The Scyphozoa, or true jellyfish, polyps (Strong 1925). are large, have fringed mouth lobes, scal- Color: loped margins, no velum, and a complex pat- Body: tern of radial canals (Rees and Hand 1975). Pedicel: The polyp is pedicel- Some scyphozoans also have prominent, late (Kozloff 1987; Mills et al. 2007), with hy- pendant oral arms. Very young A. victoria, up drocaulus (stem) up to 2.5 mm in length, to 4 mm in diameter, can look similar to Poly- and is ringed rather than spirally grooved orchis penicillatus in shape (Fig. 6); addition- (Mills et al. 2007). ally, the young A. victoria lack the many radial Hydranth: Each polyp has canals that they will develop as they mature, about twenty tentacles, a mouth, and an in- and so seem more similar to the P. penicilla- tertentacular web armed with nematocysts. tus with its four radial canals (Russell 1953). The colonies are stolonal (connected by hor- Ecological Information izontal shoots at the base of each hydrocaulus) (Mills et al. 2007). The hydranth is cov- Range: Type localities are Victoria Harbor, ered by a theca (hydrothecae) that is deeper British Columbia and Puget Sound, Washing- than it is wide and is able to hold the entire ton (Murbach and Shearer 1902). Found in hydranth when contracted (Mills et al. 2007; temperate waters in both northern and south- Kozloff 1987) and the hydrothecae are radi- ern hemispheres. Well known in Puget ally symmetrical and do not have true mar- Sound and British Columbia. ginal cups (Mills et al. 2007). Instead, they Local Distribution: Oregon distribution in- have longitudinal striations with straight cludes most bays and nearshore waters. walls (Mills et al. 2007; Kozloff 1987), and Habitat: Medusae are found in plankton and the opercular valves are continuations of the harbors (e.g., Charleston boat basin). The at- hydrothecal margin (Mills et al. 2007; Kozloff tached, or polyp, forms have been found inter- A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected]

tidally (Mills et al. 2007). -like. Medusae develop asexually from buds Salinity: Collected at salinities of 30 and on the colony and become free swimming. All cannot tolerate large fresh water influx (e.g., medusae from a single colony are the same from storms, MacGinitie and MacGinitie sex (diecious). Eggs are transparent and 1949). 100µm diameter (Mills and Strathmann 1987) Temperature: A cold to temperate species. and medusae spawn within several hours of Tidal Level: Medusae are pelagic, while daybreak or sundown (Mills and Strathmann polyps are intertidal. 1987). Embryos become planula larvae, Associates: The small anemone, Peachia which settle and develop into new polypoids. quinquecapitata, is sometimes parasitic on The first hydranth forms about a week after A. victoria individuals (Puget Sound, Wash- settlement, and additional hydranths grow ington). Aequorea victoria ingests P. quin- from unbranched stolons (Mills and Strath- quecapitata larvae, and once inside the hy- mann 1987). dromedusae, the larvae feed on nutrients in Larva: Embryos become tiny planula larvae. the radial canals and gonads. These parasit- Planulae are uniformly ciliated and usually ic larvae grow and metamorphose into juve- oval or club-shaped. These larvae are non- niles while still inside A. victoria. Ultimately, feeding and free-swimming. They are armed the juvenile leaves its host mid-water and with nematocytes, but lack an apical ciliary may become ectoparasitic on another A. vic- tuft and septa (see Fig. 3, Sadro 2001). These toria host (Mills and Strathmann 1987). larvae settle on their sides (Fig. 3) and be- The hydromedusae are also parasitized by come new polyps (Figs. 4, 5) (Strong 1925). larval and juvenile forms of Hyperia medu- In culture, the larvae form within 24 hours of sarum. Aequorea victoria provides a pelagic fertilization and settle within 3–12 days (Mills host on which hyperiid amphipods can over- and Strathmann 1987). winter (Boonstra et al. 2015, Towanda and Juvenile: Juveniles are free, spherical medu- Thuesen 2006). sae. They have two tentacles and scattered Abundance: Aequorea victoria is one of the exumbrellar nematocysts that form a broad most common large medusae. At the right ring on the lower half of the bell (Fig. 6) (Mills time of year, it can occur in great numbers et al. 2007 and Kozloff 1987). They are not locally. It was present in high densities in considered mature until they reach about 50 Puget Sound, Washington, from the early mm in diameter (Mills and Strathmann 1987). 1960s to the mid-1990s. At that time, thou- Juvenile recruitment occurs in the spring sands were collected by researchers for (Larson 1986). their aequorin (luminescent protein) and Longevity: Unknown. GFP (Green Fluorescent Protein). Since the Growth Rate: Medusae grow very quickly, mid-1990s, A. victoria populations have de- especially as compared to anthozoans creased in both number and size, though (MacGinitie and MacGinitie 1949). In labora- this trend may be due to environmental tory conditions they grow from egg to polyp in change as well as high takes (Friday Har- less than six days (Strong 1925). bor) (Mills 2001). Food: Their diet consists predominately of soft-bodied prey (e.g. ctenophores, medusae, Life-History Information cannery refuse), but they also eat mature Reproduction: Hydrozoans provide a good crustaceans, crustacean larvae (Purcell example of alternation of generations. The 1989), and polychaetes. They are an im- sessile, polypoid colony is delicate and plant portant predator of fish larvae and eggs

(Purcell 1989), but once the fish larvae pass of Georgia planktonic coelenterates: labor- the post-yolksac stage they are better able atory evidence. Canadian Journal of Fish- to escape the medusae and are less com- eries and Aquatic Sciences. 37:120-123. monly preyed upon (Purcell et al. 1987). 4. BOONSTRA, J. L., M. E. KONEVAL, J. D. They also participate in intraguild predation, CLARK, M. SCHICK, M. SMITH, and A. L. eating other gelatinous species that com- STARK. 2015. Milbemycin oxime pete for zooplankton (Purcell 1991). Their (interceptor) treatment of amphipod para- feeding response is mostly tactile (Hyman sites (Hyperiidae) from several host jelly- 1940) (i.e. they use their tentacles to capture fish species. Journal of Zoo and Wildlife prey, Purcell et al. 1987). Additionally, they Medicine. 46:158-160. can sense water-born chemicals produced 5. HYMAN, L. H. 1940. The Invertebrates: by crustacean prey, Artemia (Arai 1991), Protozoa through Ctenophora. McGraw- though further research is required to fully Hill, New York, London. understand this behavior. 6. KOZLOFF, E. N. 1983. Seashore life of Predators: Aequorea victoria is well protect- the northern Pacific coast. University of ed by nematocysts (stinging cells). Giant Washington Press, Seattle. sunfish (Mola mola) eat them, as do some 7. —. 1987. Marine invertebrates of the Pa- nudibranchs and the hydromedusae Stomo- cific Northwest. University of Washington toca atra (Arai and Jacobs 1980) and Pha- Press, Seattle. cellophora camtschatica (Towanda and 8. LARSON, R. J. 1986. Seasonal changes Thuesen 2006). in the standing stocks, growth rates, and Behavior: The small polypoid stage reproduction rates of gelatinous predators in quires a well-sheltered place in order to at- Saanich Inlet, British Columbia. Marine tach. The floating medusa is the stage most Ecology Progress Series. 33:89-98. commonly seen (Figs. 1, 2), but often exhib- 9. MACGINITIE, G. E., and N. MACGINITIE. its high mortality after a storm or a sudden 1949. Natural history of marine animals. pulse of fresh water (MacGinitie and Mac- McGraw-Hill Book Co., New York. Ginitie 1949). Aequorea victoria medusae 10. MILLS, C. E. 2001. Jellyfish blooms: are are luminescent when stimulated, and pro- populations increasing globally in re- vided the original source for the commonly- sponse to changing ocean conditions? Hy- used green fluorescent protein (GFP) and drobiologia. 451:55-68. the luminescent protein aequorin (Mills et al. 11. MILLS, C. E., A. C. MARQUES, A. E. 2007). MIGOTTO, D. R. CALDER, C. HAND, J. T. REES, S. H. D. HADDOCK, C. W. Bibliography DUNN, and P. R. PUGH. 2007. Hydrozoa: 1. ARAI, M. N. 1991. Attraction of Aurelia polyps, hydromedusae, and siphonophora, and Aequorea to prey. Hydrobiologia. p. 118-167. In: The Light and Smith manu- 216:363-366. al: intertidal invertebrates from central Cal- 2. ARAI, M. N., and A. BRINCKMANN- ifornia to Oregon. J. T. Carlton (ed.). Uni- VOSS. 1980. Hydromedusae of British versity of California Press, Berkeley. Columbia and Puget Sound. Canadian 12. MILLS, C. E., and M. F. STRATHMAN. Bulletin of Fisheries and Aquatic Scienc- 1987. Phylum Cnidaria, Class Hydrozoa, es. 204:1-192. p. 44-71. In: Reproduction and develop- 3. ARAI, M. N., and J. R. JACOBS. 1980. ment of marine invertebrates of the north- Interspecific predation of common Strait ern Pacific coast: data and methods for

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected]

the study of eggs, embryos, and larvae. certain Puget Sound hydroids and medu- M. F. Strathman (ed.). University of sae. III:383-399. Washington Press, Seattle, WA. 22. TOWANDA, T., and E. V. THUESEN. 13. MURBACH, L., and G. SHEARER. 1902. 2006. Ectosymbiotic behavior of Cancer Preliminary report on a collection of me- gracilis and its trophic relationships with its dusae from the coast of British Columbia host Phacellophora camtschatica and the and Alaska. Annals of Natural History. parasitoid Hyperia medusarum. Marine 7:pp. 71-73. Ecology Progress Series. 315:221-236. 14. PURCELL, J. E. 1989. Predation on fish Updated 2015 Ae- larvae and eggs by the hydromedusa C.D. Piazzola and T.C. Hiebert quorea victoria at a herring spawning ground in British Columbia. Canadian Journal of Fisheries and Aquatic Scienc- es. 46:1415-1427. 15. —. 1991. Predation by Aequorea victoria on other species of potentially competing pelagic hydrozoans. Marine Ecology Pro- gress Series. 72:255-260. 16. PURCELL, J. E., T. D. SIFERD, and J. B. MARLIAVE. 1987. Vulnerability of larval herring (Clupea harengus pallasi) to capture by the jellyfish Aequorea victoria. Marine Biology. 94:157-162. 17. REES, J. T., and C. H. HAND. 1975. Class Hydrozoa, p. 65-84. In: Light's manual: intertidal invertebrates of the central California coast. S. F. Light, R. I. Smith, and J. T. Carlton (eds.). University of California Press, Berkeley. 18. RUSSELL, F. S. 1953. The Medusae of the British Isles. University Press, Cam- bridge. 19. SADRO, S. 2001. Cnidaria (Coelenterata), p. 13-23. In: An identifica- tion guide to the larval marine invertebrates of the Pacific Northwest. A. L. Shanks (ed.). Oregon State University, Corvallis. 20. SCHUCHERT, P. 2015. Aequorea victoria (Murbach & Shearer, 1902), World Register of Marine Species: http:// www.marinespecies.org/aphia.php? p=taxdetails&id=283998. [Accessed 7/24/2015]. 21. STRONG, L. H. 1925. Development of