Nematostella Vectensis Class: Anthozoa, Hexacorallia

Nematostella vectensis Class: Anthozoa, Hexacorallia

Order: Actiniaria, Anenthemonae Starlet sea anemone Family: Edwardsioidea, Edwardsiidae

Taxonomy: Nematostella vectensis was de- than wide, cylindrical, and transparent. The scribed by Stephenson in 1935. Nematostel- eight mesenteries are visible through its walls. la pellucida is a synonym (Hand 1957). In There is a thin capitulum (collar) around the the larger taxonomic scale, the subclass Zo- oral disc at the top of the column (Williams antharia has been synonymized with Hexa- 1975). There is a single ventral siphonoglyph corallia (Hoeksema 2015). (Williams 1975). Oral Disc: There is no inner ring Description Medusa: No medusa stage in Anthozoans of tentacles, and there are no siphonoglyphs, on the oral disc. Polyp: Tentacles: Tentacles are retrac- Size: The column (Fig. 1) can be up tile, cylindrical, and tapered. They are not to 15 mm long in the field, but can grow capitate, or knobbed. Though they can vary much longer (160 mm) when raised in the from 12-18, there are usually 16 (Stephenson laboratory (Hand and Uhlinger 1992; Fautin 1935; Fautin and Hand 2007). There are 6-7 and Hand 2007). The maximum diameter is outer (exocoelic) tentacles that are longer 4 mm at the base near the bulb (physa) than inner (endocoelic) tentacles, and are of- (Hand 1957) and increases to 8 mm at the ten reflexed down the column (they can be crown of tentacles; the diameter is not often longer than column). The inner tentacles can this large, and a more average diameter of be raised above the mouth (Fig. 1), and can the column is 2.5 mm. have white spots on their inner edges Color: The anemone is white and (Crowell 1946). Nematosomes can be seen transparent when expanded (Fautin and moving inside the tentacles. Hand 2007), while the internal color de- Mesenteries: Mesenteries are pends on food. vertical partitions (eight in this species) below Body: Nematostella vectensis is radi- the gullet and visible through the column. ally symmetrical, consisting of a tall cylinder Gonads appear as thickened bands on the and a crown of tentacles. Aberrant forms mesenteries (Fig. 3) (Lindsay 1975). Eggs are (e.g., two headed, tentacleless) are found as produced from these partitions. The mesen- well (Williams 1976). The body is slightly teries can be green, brown, black, etc., de- worm-like, in that the column is longer than it pending on food (Williams 1975). is wide (Fautin et al. 1987). Usually, the Pedal Disc: The physa is a anemone is buried up to its oral disc and swollen, bulb-like burrowing structure at the tentacles (Fautin and Hand 2007). Mesen- base of the column (Fig. 1), which replaces teries divide the internal structure and can- the pedal disc of other anemones. It is cov- not be seen through the body walls. On the ered with rugae (ridges), which secrete mucus oral disc, specimens occasionally have cili- and aid in digging and climbing (Williams ated grooves to direct water 1975). Nematostella vectensis does not at- (siphonoglyphs). tach to solid substrate, but rather burrows into Column: The column is longer

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. Nematostella vectensis. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Com- mon 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.

muddy habitats (Fautin et al. 1987). North America from California to Washington Cnidae: According to Matus et al. (Hand and Uhlinger 1992; Fautin and Hand (2007), there are three types of cnidae in 2007). this species: basitrichs, microbasic basit- Local Distribution: Locally, N. vectensis is richs, and spirocysts. found at five sites in Coos Bay, including in Nematosomes: These are rather South Slough, near downtown Coos Bay, and mysterious spherical, ciliated bodies, some- at the mouth of Coos River. times found in the coelenteron (digestive Habitat: This species is primarily estuarine (in cavity) and in tentacles (Fautin et al. 1987) temperate northern estuaries), and is com- (Fig. 2). They contain nematocysts (Hand mon in shallow pools of salt marshes (Fautin and Uhlinger 1992), and their function is not et al. 1987; Fautin and Hand 2007). It often known. lives in pondweed masses, like soft muds of Salicornia marshes; Ruppia, Cladophora, and Possible Misidentifications Chaetomorpha ponds (New England); and This is the only species of the genus Enteromorpha and Vaucheria ponds (Coos Nematostella known in the temperate north- Bay) (Williams 1976). These anemones are ern hemisphere. Nematostella polaris, a sensitive to pollution, and so will not be found similar Arctic anemone, lives under condi- in habitats that become contaminated tions which N. vectensis could tolerate. They (Williams 1976). are not believed to be the same species Salinity: Nematostella vectensis can tolerate (Hand 1957). There is certainly no other a wide range of salinities, from less than 50% very small, mud-dwelling burrowing anemo- seawater to over 100% in Coos Bay (Hand ne in our area, which could be confused with 1957). It is an osmoconformer, has been N. vectensis. found from 8 to 38, and is very adaptable to Flosmaris grandis is another elon- salinity changes (Inouye 1976). gate, mud-burrowing, translucent anemone, Temperature: This species lives in a wide but it is usually very large (to 50 cm), has range of temperatures; in northern California over 24 tentacles, and instead of a physa, alone, it can be found from 0-30° C (Hand has a basal disc attached to something solid 1957). It has been kept for long periods in the (Fautin and Hand 2007). This species also lab at 21-22° C (Inouye 1976). In Coos Bay has acontia (defensive tentacles that ex- (South Slough), it ranges from 6-18° C (ibid). trude through the column), which N. vecten- Tidal Level: This anemone is generally found sis lacks (Fautin and Hand 2007). Diadu- in salt marsh tide pools above + 3 ft, but is mene sp. are often long and pale, but they sometimes found living subtidal (Hand and have pigmentation of some sort and don't Uhlinger 1992). burrow. Only N. vectensis of these anemo- Associates: It often lives in association with nes has nematosomes. the algae Distichlis, Salicornia, and Entero- Ecological Information morpha; the diatom Vaucheria; and the inver- Range: The type locality is the Isle of Wight, tebrates nemerteans, polychaete larvae, har- where it likely no longer exists due to de- pacticoid copepods, ciliates, sphaeromid iso- struction of habitat (Williams 1975). Its range pods, and gammarid amphipods. covers the Atlantic coasts of Europe; from Abundance: A rarely occurring animal, it can Florida to Louisiana in the Gulf of Mexico; be densely abundant over a small area where the east coast of North America from Nova it does occur (Hand and Uhlinger 1992). Be- Scotia to Georgia; and the west coast of cause of its sensitivity to pollution, it quickly 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]

retreats from areas where the habitat is four tentacles and is 250-500 µm long (Hand compromised. and Uhlinger 1992). This process occurs about a week after fertilization. Two to three Life-History Information weeks after fertilization it grows more tenta- Reproduction: This anemone propagates cles and has formed all eight mesenteries using both sexual and asexual reproduction. (Hand and Uhlinger 1992). It is dioecious (separate sexes) (Hand and Longevity: Specimens have been kept in lab Uhlinger 1992), and its gonads on the mes- for up to five years (Hand and Uhlinger 1992). enteries produce gametes. Animals are Growth Rate: This species can grow from found with developed gonads in summer fertilization to sexual maturity in 69 days, and fall (Williams 1976), but in laboratory though the process usually takes three to four settings they will reproduce year-round months (Hand and Uhlinger 1992). (Hand and Uhlinger 1992). Egg production Food: Like other anemones, N. vectensis is can be induced in lab by lowering salinity an active predator, using tentacles with sting- (Lindsay 1975); the eggs are released in ing nematocysts to capture prey. Its diet sticky, gelatinous egg masses that also con- largely consists of the snail Hydrobia (New tain nematosomes (Hand and Uhlinger England, Nova Scotia) (Frank 1978), cope- 1992). In lab these anemones can maintain pods, midge larvae, egg masses, crustacean a schedule of spawning once a week (Hand remains, ostracods, varied worms, corixids, and Uhlinger 1992). Sexual reproduction rotifers, and veliger larvae (Hand and Uhlinger produces planula larvae, which settle as 1994). It is unique in that it also eats insects new polyps. There is no medusoid stage. It (Hand and Uhlinger 1994). In lab, in can be takes two to three days for the fertilized egg fed Artemia nauplii, bivalve veliger larvae, to grow to a planula, and seven days to set- mussel tissue, and yolk from hard-boiled hen ting into a juvenile (Hand and Uhlinger eggs (Hand and Uhlinger 1992). 1992). Asexual reproduction is also possible Predators: This species is an important prey by transverse binary fission (Fautin and item for the grass shrimp Palaemonetes pugio Hand 2007). This division can occur in two (Kneib 1985). As of 2008, this shrimp was the ways. In the first (physal pinching), the col- only known predator of N. vectensis (Moran et umn constricts until a piece of the physa is al. 2008). divided from the rest of the body. This piece Behavior: Specimens are usually buried to develops into a full clonal anemone. In the the tentacles, but they are also found extend- second, less common way (polarity rever- ed over the mud. The anemone can move by sal), the aboral end of the anemone devel- short, peristaltic-like movements, or by throw- ops into an oral structure, and the anemone ing itself (Lindsay 1975). It secretes a mucus pinches off in the middle to yield two fully- "tube" to protect its epidermis (Crowell 1946). formed anemones (Darling et al. 2005). This species has also become an important Larva: Spherical ciliated planula larvae de- specimen in genetic research due to its short velop 2 days after fertilization (Hand and Uh- generation time and tolerance to most condi- linger 1992). They will change shape as they tions, among other reasons (Hand and Uh- develop to become elongate and have an linger 1992; Darling et al. 2005), and its ge- apical tuft (Hand and Uhlinger 1992). They nome has been mapped (Putnam et al. 2007). actively swim using the cilia on their apical tuft (Sadro 2001). Bibliography Juvenile: When it settles, the juvenile has 1. CROWELL, S. 1946. A new sea anemone

from Woods Hole, Massachusetts. Jour- 10. INOUYE, S. 1976. Tolerance of salinity nal of the Washington Academy of Sci- fluctuation by the estuarine sea anemone, ences. 36:57-60. Nematostella vectensis. Vol. Summer 2. DARLING, J. A., A. R. REITZEL, P. M. Book 1, Oregon Institute of Marine Biolo- BURTON, M. E. MAZZA, J. F. RYAN, J. gy, Charleston, OR. C. SULLIVAN, and J. R. FINNERTY. 11. KNEIB, R. T. 1985. Predation and disturb- 2005. Rising starlet: the starlet sea ance by grass shrimp, Palaemonetes pu- anemone, Nematostella vectensis. Bi- gio Holthuis, in soft-substratum benthic oessays. 27:211-221. invertebrate assemblages. Journal of Ex- 3. FAUTIN, D. G., and C. HAND. 2007. An- perimental Marine Biology and Ecology. thozoa, p. 173-184. In: The Light and 93:91-102. Smith Manual: intertidal invertebrates 12. LINDSAY, J. A. 1975. A salt marsh anem- from central California to Oregon. J. T. one. Marine Aquarist. 6:43-48. Carlton (ed.). University of California 13. MATUS, D. Q., K. PANG, M. DALY, and Press, Berkeley. M. Q. MARTINDALE. 2007. Expression of 4. FAUTIN, D. G., A. E. SIEBERT, and E. Pax gene family members in the anthozo- N. KOZLOFF. 1987. Class Anthozoa, p. an cnidarian, Nematostella vectensis. Evo- 68-78. In: Marine invertebrates of the Pa- lution & Development. 9:25-38. cific Northwest. E. N. Kozloff (ed.). Uni- 14. MORAN, Y., H. WEINBERGER, A. M. versity of Washington Press, Seattle. REITZEL, J. C. SULLIVAN, R. KAHN, D. 5. FRANK, P. G., and J. S. BLEAKNEY. GORDON, J. R. FINNERTY, and M. 1978. Asexual reproduction, diet and GUREVITZ. 2008. Intron retention as a anomalies of the anemone Nematostella posttranscriptional regulatory mechanism vectensis in Nova Scotia. Canadian Field of neurotoxin expression at early life stag- -Naturalist. 92:259-263. es of the starlet anemone Nematostella 6. HAND, C. 1957. Another sea anemone vectensis. Journal of Molecular Biology. from California and the types of certain 380:437-443. California anemones. Journal of the 15. PUTNAM, N. H., M. SRIVASTAVA, U. Washington Academy of Sciences. HELLSTEN, B. DIRKS, J. CHAPMAN, A. 47:411-414. SALAMOV, A. TERRY, H. SHAPIRO, E. 7. HAND, C., and K. R. UHLINGER. 1992. LINDQUIST, V. V. KAPITONOV, J. The culture, sexual and asexual repro- JURKA, G. GENIKHOVICH, I. V. duction, and growth of the sea anemone GRIGORIEV, S. M. LUCAS, R. E. Nematostella vectensis. Biological Bulle- STEELE, J. R. FINNERTY, U. TECHNAU, tin. 182:169-176. M. Q. MARTINDALE, and D. S. ROKH- 8. —. 1994. The unique, widely distributed, SAR. 2007. Sea anemone genome re- estuarine sea anemone, Nematostella veals ancestral eumetazoan gene reper- vectensis Stephenson: A review, new toire and genomic organization. Science. facts, and questions. Estuaries. 17:501- 317:86-94. 508. 16. SADRO, S. 2001. Cnidaria (Coelenterata), 9. HOEKSEMA, B. 2015. Hexacorallia. Vol. p. 13-23. In: An identification guide to the 2015, World Register of Marine Species: larval marine invertebrates of the Pacific http://www.marinespecies.org/aphia.php? Northwest. A. L. Shanks (ed.). Oregon p=taxdetails&id=1340. [Accessed State University, Corvallis. 9/23/2015]. 17. STEPHENSON, T. A. 1935. The British

sea anemones. The Ray Society, Lon- don. 18. WILLIAMS, R. B. 1975. A redescription of the brackish-water sea anemone Nematostella vectensis Stephenson, with an appraisal of congeneric species. Jour- nal of Natural History. 9:51-64. 19. —. 1976. Conservation of the sea anemone Nematostella vectensis in Norfolk, England, and its world distribution. Transactions of the Norfolk and Norwich Naturalists' Society. 23:257-266. Updated 2015 C.D. Piazzola and T.C. Hiebert