Metridium Senile Class: Anthozoa, Hexacorallia

Metridium senile Class: Anthozoa, Hexacorallia

Order: Actiniaria, Enthemonae Plumose or frilled anemone Family: Metridioidea, Metridiidae

Taxonomy: Metridium senile was first de- cinclides (pores through which acontia can scribed by Linnaeus in 1761. When it was protrude) are sometimes visible as dark spots first described, scientists believed that there (Fautin et al. 1987). The tentacles are grey to was only one, very diverse species of white, and there is usually a ring of white Metridium: M. senile. Hand (1955) took the around the mouth (Kozloff 1983). Because of first step in dividing this species by distin- asexual reproduction, all animals in one area guishing the Atlantic and Pacific populations may be same color. as subspecies. Since then, further work has Body: This anemone is cylindrical with been done to determine the genetic lines many fine short tentacles. Mesenteries divide that should be drawn in Metridium sea the internal structure and cannot be seen anemones. Bucklin and Hedgecock (1982) through the body walls. Defensive tentacles determined that the clonal M. senile, the sol- called acontia can extend through pores itary M. senile, and the recently (at the time) called cinclides in the column. The parapet described M. exilis were genetically distinct rings the end of the column, from which the species. The clonal species kept the name capitulum extends distally. On the oral disc, M. senile, while the solitary species gained specimens occasionally have ciliated grooves the name M. gigantus, which then became to direct water (siphonoglyphs). M. farcimen (Fautin and Hand 2000). There Column: The column is stout. It is still some debate on the matter. Recent is compact in young specimens and often studies are suggesting that the Atlantic sub- long in old ones. It is not striped (Perkins species of M. senile may actually be M. di- 1977). anthus, but further research is necessary to Collar: A parapet (collar) is fully understand this relationship (Fautin and seen beneath the crown of tentacles (Fig. 2). Sebens 1987; Fautin 2013; Fautin 2015). Oral Disc: There is very little In the larger taxonomic scale, the tentacle-free area around mouth (Fautin and subclass Zoantharia has been synonymized Hand 2007). Siphonoglyphs (ciliated grooves) with Hexacorallia (Hoeksema 2015). vary from 0-3, and one is usual (Hand 1955). It is sometimes very slightly lobed, and some- Description times it is not lobed at all (Fautin et al. 1987; Medusa: No medusa stage in Anthozoans Fautin and Hand 2007). The margin is frilled Polyp: (Fautin and Hand 2007). Size: Specimens average about 5 cm Tentacles: Tentacles are fine, (2 inches) in diameter, including tentacles. unknobbed, and short. Metridium senile can Maximum height is 10 cm, while average is have up to 18 "catch" tentacles; these are 5 cm (Fautin et al. 1987) and minimum is short, blunt and opaque near the mouth usually larger than 2 cm (Fautin et al. 1987). (Haderlie et al. 1980) and are used to attack Color: Juveniles are white. Adults anemones from another clonal group or of an- can be brown, orange, white, or grey, and other species (Ricketts et al. 1985). There are

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. and T.C. Hiebert. 2015. Metridium senile. 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 Biol- ogy, Charleston, OR.

varied accounts of the maximum number of 2000; Eash-Loucks and Fautin 2012). M. far- tentacles, but some say that this anemone cimen also has a highly lobed oral disc, while cannot have more than 100 (Fautin et al. the oral disc of M. senile is simply circular 1987. Tentacles arranged in lappet-like (Fautin and Hand 2007). Finally, the two spe- groups or lobes (Fig. 1). Acontia are thread- cies have different kinds of cnidae on their like tentacles that are found in the lower part acontia (Fautin and Hand 2000). Many older of mesenteries. They are discharged descriptions of M. senile are actually of M. far- through the lower column wall when the ani- cimen. mal is disturbed (Fautin et al. 1987). Ecological Information Mesenteries: These are verti- Range: The type locality is San Francisco cal body cavity partitions. There can be 3-15 Bay (Hand 1955). This species is circumpolar pairs in this anemone, but they are not visi- in the northern hemisphere. They are found in ble through the body wall, as the animal is harbors and bays in both the Atlantic and Pa- opaque. cific Oceans. On the Pacific Coast, they can Pedal Disc: This is flat and be found from Sitka, Alaska, to Santa Barba- attached to a hard surface. ra, California. Cnidae: There are several kinds of Local Distribution: Locally, M. senile is cnidae present (Hand 1955), especially in found on protected pilings in larger Oregon specimens with catch tentacles (Ricketts et estuaries, such as Coos Bay. al. 1985); (Fig. 3a, b). Some contain a toxin Habitat: This anemone likes bare, shaded with a protein fraction that dialyzable materi- pilings and rock jetties, as well as floats in al with aromatic amines. harbors or bays. It can also attach to dead Possible Misidentifications shells, the tunicate Styela, the kelp crab Pu- Anthopleura artemesia, an estuarine gettia, and barnacle tests (Ricketts et al. anemone with a white stalk, can be con- 1985). fused with young M. senile. Anthopleura ar- Salinity: Collected at 30 in Coos Bay and at temesia lives in fine sand, not on pilings, 27 in Puget Sound (communication, R. Boom- and when extended tentacles are either pink er). Because this anemone lives in estuaries, or green and are heavy. it can tolerate brackish conditions; it can sur- There are two other species of vive in salinities of ~15 (50% sea water) Metridium locally: (Shumway 1978). Metridium exilis lives under rocks and Temperature: This species is found in tem- other ledges on the open coast. It has fewer perate to cold waters (Hand 1955). Its meta- than 100 tentacles with more area around bolic rate is often positively correlated with the mouth clear of tentacles, while M. senile temperature, and it acclimates well. has very little area on the oral disc without Tidal Level: This anemone is primarily inter- tentacles. Metridium exilis has a yellow, or- tidal. It can tolerate limited exposure, and is ange or red column rather than white, found between 0.0 and -1.0 on some pilings, brown, or grey (Fautin and Hand 2007). especially in summer (Kozloff 1983). It is most Metridium farcimen was once consid- abundant at slightly above mean low low wa- ered conspecific with M. senile. Where M. ter intertidal (Fautin et al. 1987; Fautin and senile is smaller, intertidal, and clonal, M. Hand 2007). farcimen is large (up to a meter in height), Associates: In Puget Sound, M. senile is of- subtidal, and solitary (Fautin and Hand ten found in conjunction with Diadumene line-

ata. On protected pilings, it frequently lives ing planula larvae (Fautin and Sebens 1987). with the sea star Pisaster and the tunicates They are ovaloid to cylindrical, covered in cil- Styela and Cnemidocarpa (Ricketts et al. ia, and have an apical tuft. They actively swim 1985). Both juveniles and adults of the sea using the cilia on their apical tuft (Sadro spider Pycnogonum litorale parasitize M. se- 2001). nile by sticking their proboscis through the Juvenile: Juveniles from sexual reproduction anemone’s body wall and ingesting their are recruited annually (Hoffmann 1987). How- body fluids (Wilhelm et al. 1997). ever, this larval recruitment is less common Abundance: Metridium senile is often found that juveniles created through asexual repro- on pilings, floats, and jetties of both Pacific duction; it is possible that predator Aeolidia and Atlantic bays and harbors. It is especial- papillosa is responsible for limiting the surviv- ly abundant in dark quiet corners, and tends al of small, young anemones (Hoffmann to live in clonal clusters (Fautin and Hand 1987). 2007). Longevity: This species survives well in small aquaria with running seawater. Life-History Information Growth Rate: The time from pedal laceration Reproduction: Like other anemones, this to a complete (abet small) anemone is about species reproduces both sexually and asex- three weeks (Fautin et al. 1987). ually. Sexually, M. senile is oviparous and Food: Metridium senile is an active predator dioecious (has separate sexes). It discharg- and carnivore. It eats very small organisms, es eggs or sperm from its mouth into the wa- unlike many anemones which manage larger ter in broadcast spawning (Kozloff 1983). prey (Kozloff 1983). Also eats algae Entero- Sperm is released first, and its presence morpha intestinalis and Desmarestia viridis triggers the females to release their eggs (Perkins 1977). Copepods and other varied (Ricketts et al. 1985). For most specimens, larvae, without preferential selection (Ricketts sexual reproduction occurs annually et al. 1985). (Hoffmann 1987). Sperm have wedge Predators: This species is popular food for shaped heads, while eggs are pinkish and nudibranchs like Hermissenda crassicornis, about 0.1 mm diameter. The sperm and Aeolidiella chromosoma, Aeolidiella oliviae eggs fertilize to create a planular larva, (McDonald 2007), and Aeolidia papillosa which settles as a young anemone. Asexual- (MacGinitie and MacGinitie 1968; Ricketts et ly, these anemones can reproduce through al. 1985). pedal laceration and, less commonly, Behavior: In dense groups of small animals, through longitudinal fission (Kozloff 1983). In catch tentacles, used for stinging rather than pedal laceration, a small amount of the pe- feeding, serve to keep anemones separate dal disc is left on substrate as anemone (Haderlie et al. 1980). At low tide they can be moves about; each small clump forms a new seen on the sides of pilings hanging "fully re- anemone (Fautin and Hand 2007). Asexual laxed and pendulous" (Ricketts et al. 1985). reproduction accounts for the often irregular siphonoglyphs and mesenteries, which Bibliography M. senile make a poor choice for lab use 1. BUCKLIN, A., and D. HEDGECOCK. (Hyman 1940). Peak of the breeding season 1982. Biochemical genetic evidence for a is August to September (Fautin and Sebens 3rd species of Metridium (Coelenterata, 1987). Actiniaria). Marine Biology. 66:1-7. Larva: This species produces pelagic feed- 2. EASH-LOUCKS, W. E., and D. G.

FAUTIN. 2012. Taxonomy and distribu- Central California. Part III. The Acontiarian tion of sea anemones (Cnidaria: Actiniar- anemones. Wasmann Journal of Biology. ia and Corallimorpharia) from deep water 13:190-206. of the northeastern Pacific. Zootaxa:1-80. 11. HOEKSEMA, B. 2015. Hexacorallia. Vol. 3. FAUTIN, D. G. 2013. Hexacorallians of 2015, World Register of Marine Species: the World, http://geoportal.kgs.ku.edu/ http://www.marinespecies.org/aphia.php? hexacoral/anemone2/index.cfm. p=taxdetails&id=1340. [Accessed [Accessed 10/22/2015]. 9/23/2015]. 4. —. 2015. Metridum senile (Linnaeus, 12. HOFFMANN, R. J. 1987. Short-term sta- 1761). In: Hexacorallians of the World. D. bility of genetic structure in populations of G. Fautin (ed.), World Register of Marine the sea anemone Metridium senile. Marine Species: http://www.marinespecies.org/ Biology. 93:499-507. aphia.php?p=taxdetails&id=100982. 13. HYMAN, L. H. 1940. The Invertebrates: [Accessed 10/22/2015]. Protozoa through Ctenophora. McGraw- 5. FAUTIN, D. G., and C. HAND. 2000. Hill, New York, London. Metridium farcimen, the valid name of a 14. KOZLOFF, E. N. 1983. Seashore life of common north Pacific sea anemone the northern Pacific coast. University of (Cnidnria: Actiniaria: Acontiaria). Pro- Washington Press, Seattle. ceedings of the Biological Society of 15. MACGINITIE, G. E., and N. MACGINITIE. Washington. 113:1151-1161. 1968. Natural history of marine animals. 6. —. 2007. Anthozoa, p. 173-184. In: The McGraw-Hill Book Co., New York. Light and Smith Manual: intertidal inver- 16. MCDONALD, G. R. 2007. Sacoglossa and tebrates from central California to Ore- Nudibranchia, p. 788-807. In: The Light gon. J. T. Carlton (ed.). University of Cal- and Smith manual: intertidal invertebrates ifornia Press, Berkeley. from central California to Oregon. J. T. 7. FAUTIN, D. G., and K. P. SEBENS. Carlton (ed.). University of California 1987. Phylum Cnidaria, Class Anthozoa, Press, Berkeley, CA. p. 83-104. In: Reproduction and develop- 17. PERKINS, E. G. 1977. Metridium senile: a ment of marine invertebrates of the clonal formation analysis. Vol. Summer: northern Pacific coast. M. F. Strathmann Book 4. Oregon Institute of Marine Biology (ed.). University of Washington Press, (University of Oregon), Charleston, OR. Seattle. 18. RICKETTS, E. F., J. CALVIN, J. W. 8. FAUTIN, D. G., A. E. SIEBERT, and E. HEDGEPETH, and D. W. PHILLIPS. 1985. N. KOZLOFF. 1987. Class Anthozoa, p. Between Pacific tides. Stanford University 68-78. In: Marine invertebrates of the Pa- Press, Stanford, CA. cific Northwest. E. N. Kozloff (ed.). Uni- 19. SADRO, S. 2001. Cnidaria (Coelenterata), versity of Washington Press, Seattle. p. 13-23. In: An identification guide to the 9. HADERLIE, E. C., C. HAND, and W. B. larval marine invertebrates of the Pacific GLADFELTER. 1980. Cnidaria Northwest. A. L. Shanks (ed.). Oregon (Coelenterata): the sea anemones and State University, Corvallis. allies, p. 40-75. In: Intertidal invertebrates 20. SHUMWAY, S. E. 1978. Activity and respi- of California. R. H. Morris, D. P. Abbott, ration in anemone, Metridium senile (L) and E. C. Haderlie (eds.). Stanford Uni- exposed to salinity fluctuations. Journal of versity Press, Stanford. Experimental Marine Biology and Ecology. 10. HAND, C. 1955. The sea anemones of 33:85-92.

21. WILHELM, E., D. BUCKMANN, and K. H. TOMASCHKO. 1997. Life cycle and population dynamics of Pycnogonum litorale (Pycnogonida) in a natural habitat. Marine Biology. 129:601-606.

Updated 2015 C.D. Piazzola and T.C. Hiebert