Metridium Senile Class: Anthozoa, Hexacorallina Order: Actinaria Plumose Or Frilled Anemone Family: Metridiidae

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Phylum: Cnidaria Metridium senile Class: Anthozoa, Hexacorallina Order: Actinaria Plumose or frilled anemone Family: Metridiidae

Taxonomy: asexual reproduction, all animals in one area Metridium senile was first described by may be same color. Linnaeus in 1761. When it was first described, Body: This anemone is cylindrical with scientists believed that there was only one, many fine short tentacles. Mesenteries divide very diverse species of Metridium: M. senile. the internal structure and cannot be seen Hand (1955) took the first step in dividing this through the body walls. Defensive tentacles species by distinguishing the Atlantic and called acontia can extend through pores Pacific populations as subspecies. Since called cinclides in the column. The parapet then, further work has been done to rings the end of the column, from which the determine the genetic lines that should be capitulum extends distally. On the oral disc, drawn in Metridium sea anemones. Bucklin specimens occasionally have ciliated grooves and Hedgecock (1982) determined that the to direct water (siphonoglyphs). clonal M. senile, the solitary M. senile, and Column: The column is stout. the recently (at the time) described M. exilis It is compact in young specimens and often were genetically distinct species. The clonal long in old ones. It is not striped (Perkins species kept the name M. senile, while the 1977). solitary species gained the name M. gigantus, Collar: A parapet (collar) is which then became M. farcimen (Fautin and seen beneath the crown of tentacles (Fig. 2). Hand 2000). There is still some debate on the Oral Disc: There is very little matter. Recent studies are suggesting that tentacle-free area around mouth (Fautin and the Atlantic subspecies of M. senile may Hand 2007). Siphonoglyphs (ciliated grooves) actually be M. dianthus, but further research vary from 0-3, and one is usual (Hand 1955). is necessary to fully understand this It is sometimes very slightly lobed, and relationship (Fautin and Sebens 1987; Fautin sometimes it is not lobed at all (Fautin et al. 2013; Fautin 2015). 1987; Fautin and Hand 2007). The margin is In the larger taxonomic scale, the subclass frilled (Fautin and Hand 2007). Zoantharia has been synonymized with Tentacles: Tentacles are fine, Hexacorallia (Hoeksema 2015). unknobbed, and short. Metridium senile can have up to 18 "catch" tentacles; these are Description short, blunt and opaque near the mouth Medusa: No medusa stage in Anthozoans (Haderlie et al. 1980) and are used to attack Polyp: anemones from another clonal group or of Size: Specimens average about 5 cm another species (Ricketts et al. 1985). There (2 inches) in diameter, including tentacles. are varied accounts of the maximum number Maximum height is 10 cm, while average is 5 of tentacles, but some say that this anemone cm (Fautin et al. 1987) and minimum is cannot have more than 100 (Fautin et al. usually larger than 2 cm (Fautin et al. 1987). 1987. Tentacles arranged in lappet-like Color: Juveniles are white. Adults can groups or lobes (Fig. 1). Acontia are be brown, orange, white, or grey, and threadlike tentacles that are found in the cinclides (pores through which acontia can lower part of mesenteries. They are protrude) are sometimes visible as dark spots discharged through the lower column wall (Fautin et al. 1987). The tentacles are grey to when the animal is disturbed (Fautin et al. white, and there is usually a ring of white 1987). around the mouth (Kozloff 1983). Because of

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12641 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Mesenteries: These are Local Distribution: Locally, M. senile is vertical body cavity partitions. There can be 3- found on protected pilings in larger Oregon 15 pairs in this anemone, but they are not estuaries, such as Coos Bay. visible through the body wall, as the animal is Habitat: This anemone likes bare, shaded opaque. pilings and rock jetties, as well as floats in Pedal Disc: This is flat and harbors or bays. It can also attach to dead attached to a hard surface. shells, the tunicate Styela, the kelp crab Cnidae: There are several kinds of Pugettia, and barnacle tests (Ricketts et al. cnidae present (Hand 1955), especially in 1985). specimens with catch tentacles (Ricketts et al. Salinity: Collected at 30 in Coos Bay and at 1985); (Fig. 3a, b). Some contain a toxin with 27 in Puget Sound (communication, R. a protein fraction that dialyzable material with Boomer). Because this anemone lives in aromatic amines. estuaries, it can tolerate brackish conditions; it can survive in salinities of ~15 (50% sea Possible Misidentifications water) (Shumway 1978). Anthopleura artemesia, an estuarine Temperature: This species is found in anemone with a white stalk, can be confused temperate to cold waters (Hand 1955). Its with young M. senile. Anthopleura artemesia metabolic rate is often positively correlated lives in fine sand, not on pilings, and when with temperature, and it acclimates well. extended tentacles are either pink or green Tidal Level: This anemone is primarily and are heavy. intertidal. It can tolerate limited exposure, and There are two other species of Metridium is found between 0.0 and -1.0 on some locally: pilings, especially in summer (Kozloff 1983). It Metridium exilis lives under rocks and other is most abundant at slightly above mean low ledges on the open coast. It has fewer than low water intertidal (Fautin et al. 1987; Fautin 100 tentacles with more area around the and Hand 2007). mouth clear of tentacles, while M. senile has Associates: In Puget Sound, M. senile is very little area on the oral disc without often found in conjunction with Diadumene tentacles. Metridium exilis has a yellow, lineata. On protected pilings, it frequently lives orange or red column rather than white, with the sea star Pisaster and the tunicates brown, or grey (Fautin and Hand 2007). Styela and Cnemidocarpa (Ricketts et al. Metridium farcimen was once considered 1985). Both juveniles and adults of the sea conspecific with M. senile. Where M. senile is spider Pycnogonum litorale parasitize M. smaller, intertidal, and clonal, M. farcimen is senile by sticking their proboscis through the large (up to a meter in height), subtidal, and anemone’s body wall and ingesting their body solitary (Fautin and Hand 2000; Eash-Loucks fluids (Wilhelm et al. 1997). and Fautin 2012). M. farcimen also has a Abundance: Metridium senile is often found highly lobed oral disc, while the oral disc of M. on pilings, floats, and jetties of both Pacific senile is simply circular (Fautin and Hand and Atlantic bays and harbors. It is especially 2007). Finally, the two species have different abundant in dark quiet corners, and tends to kinds of cnidae on their acontia (Fautin and live in clonal clusters (Fautin and Hand 2007). Hand 2000). Many older descriptions of M. senile are actually of M. farcimen. Life-History Information Reproduction: Like other anemones, this Ecological Information species reproduces both sexually and Range: The type locality is San Francisco asexually. Sexually, M. senile is oviparous Bay (Hand 1955). This species is circumpolar and dioecious (has separate sexes). It in the northern hemisphere. They are found in discharges eggs or sperm from its mouth into harbors and bays in both the Atlantic and the water in broadcast spawning (Kozloff Pacific Oceans. On the Pacific Coast, they 1983). Sperm is released first, and its can be found from Sitka, Alaska, to Santa presence triggers the females to release their Barbara, California. eggs (Ricketts et al. 1985). For most

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 Biology, Charleston, OR. specimens, sexual reproduction occurs Behavior: In dense groups of small animals, annually (Hoffmann 1987). Sperm have catch tentacles, used for stinging rather than wedge shaped heads, while eggs are pinkish feeding, serve to keep anemones separate and about 0.1 mm diameter. The sperm and (Haderlie et al. 1980). At low tide they can be eggs fertilize to create a planular larva, which seen on the sides of pilings hanging "fully settles as a young anemone. Asexually, these relaxed and pendulous" (Ricketts et al. 1985). anemones can reproduce through pedal laceration and, less commonly, through longitudinal fission (Kozloff 1983). In pedal Bibliography laceration, a small amount of the pedal disc is left on substrate as anemone moves about; 1. BUCKLIN, A., and D. HEDGECOCK. each small clump forms a new anemone 1982. Biochemical genetic evidence (Fautin and Hand 2007). Asexual for a 3rd species of Metridium reproduction accounts for the often irregular (Coelenterata, Actiniaria). Marine siphonoglyphs and mesenteries, which make Biology. 66:1-7. M. senile a poor choice for lab use (Hyman 2. EASH-LOUCKS, W. E., and D. G. 1940). Peak of the breeding season is August FAUTIN. 2012. Taxonomy and to September (Fautin and Sebens 1987) distribution of sea anemones Larva: This species produces pelagic feeding (Cnidaria: Actiniaria and planula larvae (Fautin and Sebens 1987). Corallimorpharia) from deep water of They are ovaloid to cylindrical, covered in the northeastern Pacific. Zootaxa:1- cilia, and have an apical tuft. They actively 80. swim using the cilia on their apical tuft (Sadro 3. FAUTIN, D. G. 2013. Hexacorallians 2001). of the World, Juvenile: Juveniles from sexual reproduction http://geoportal.kgs.ku.edu/hexacoral/ are recruited annually (Hoffmann 1987). anemone2/index.cfm. [Accessed However, this larval recruitment is less 10/22/2015]. common that juveniles created through 4. —. 2015. Metridum senile (Linnaeus, asexual reproduction; it is possible that 1761). In: Hexacorallians of the World. predator Aeolidia papillosa is responsible for D. G. Fautin (ed.), World Register of limiting the survival of small, young anemones Marine Species: (Hoffmann 1987). http://www.marinespecies.org/aphia.p Longevity: This species survives well in hp?p=taxdetails&id=100982. small aquaria with running seawater. [Accessed 10/22/2015]. Growth Rate: The time from pedal laceration 5. FAUTIN, D. G., and C. HAND. 2000. to a complete (abet small) anemone is about Metridium farcimen, the valid name of three weeks (Fautin et al. 1987). a common north Pacific sea anemone Food: Metridium senile is an active predator (Cnidnria: Actiniaria: Acontiaria). and carnivore. It eats very small organisms, Proceedings of the Biological Society unlike many anemones which manage larger of Washington. 113:1151-1161. prey (Kozloff 1983). Also eats algae 6. —. 2007. Anthozoa, p. 173-184. In: Enteromorpha intestinalis and Desmarestia The Light and Smith Manual: intertidal viridis (Perkins 1977). Copepods and other invertebrates from central California to varied larvae, without preferential selection Oregon. J. T. Carlton (ed.). University (Ricketts et al. 1985). of California Press, Berkeley. Predators: This species is popular food for 7. FAUTIN, D. G., and K. P. SEBENS. nudibranchs like Hermissenda crassicornis, 1987. Phylum Cnidaria, Class Aeolidiella chromosoma, Aeolidiella oliviae Anthozoa, p. 83-104. In: Reproduction (McDonald 2007), and Aeolidia papillosa and development of marine (MacGinitie and MacGinitie 1968; Ricketts et invertebrates of the northern Pacific al. 1985). coast. M. F. Strathmann (ed.).