Pisaster Brevispinus Class: Asteroidea Order: Forcipulatida the Pink, Short-Spined Sea Star Family: Asteriidae
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Phylum: Echinodermata Pisaster brevispinus Class: Asteroidea Order: Forcipulatida The pink, short-spined sea star Family: Asteriidae Taxonomy: The genus Pisaster includes (Figs. 1, 3) and (less conspicuous) three Pacific coast sea star species, including anus. Pisaster brevispinus. One can find many Aboral Surface: Aboral surface rough and historic synonyms for P. brevispinus, including spiny in texture and pink in color. P. papulosus and P. paucispinus. Spines: Short (“brevi”, shorter than Furthermore, two subspecies were erected for other Pisaster species, Feder 1980), P. brevispinus in 1930 (Fisher) but the spines do not usually form reticulated morphological and genetic status of these pattern or crescentic arcs and there is subspecies is currently unknown. Before at least one straight row of spines being assigned to the genus Pisaster, this down each arm (Fig. 1). Spines occur species belonged to the, currently accepted, singly or in small groups of two and genus Asterias (synonyms A. brevipsina, A. three (up to five) and are separated by papulosa). areas of soft tissue (Fig. 3). Large spines are often shaped like onion Description domes. The spines in the center of Size: One of the largest asteroids worldwide the disc do not form a distinct star and typically 320 mm in diameter (Hyman (Fig. 1). 1955; Feder 1980; Mah 2007; see Madreporite: The madreporite, which http://echinoblog.blogspot.com/2008/06/giant- filters water into the interior stone pink-monsters-among-us-enter.html), with canal, is raised, with channels, and is largest reported size 900 mm (Mah and Blake a conspicuous plate on the central 2012). The illustrated specimen (from Coos disc (Fig. 1). Bay) is 190 mm in diameter. Pedicellariae: Stalked or sessile Color: Oregon specimens always pink, appendages with pincers, used for although some keys indicate gray-green or removing invaders. Pedicellariae are maroon-purple mottling (see Plate 25, Kozloff bird beak-like and two-jawed in 1993). Pisaster species. Very small General Morphology: Sea stars pedicellariae cluster around spines (Asteroidea) are conspicuous members of the (Fig. 3) and no large sessile intertidal and subtidal. Their bodies are pedicellariae are visible. Used in composed of a central disc from which arms deterring predators (e.g. Solaster or rays extend. The star-shaped body can be dawsoni, Van Veldhuizen and Oakes divided into an oral (or ventral) side where 1981). the mouth is located and aboral (or dorsal) Anus: Inconspicuous and near center side. of aboral surface. Body: Body is firm, not weak and flabby. Oral Surface: Oral surface ochre in color Rays: Five, unless damaged. Each and consists of hard, textured surface from ray is tapering and most broad where extension of aboral surface and ambulacral they join the central disc, but not broad grooves running the length of each arm and enough to give webbed appearance converging at the mouth. Grooves are fleshy (as in Patiria spp.). in texture due to thepresence of tube feet. Central Disc: Large, raised, but not Spines: Four rows of flattened set off from arms or distinctly disc-like (elliptical) blunt spines with small as in Ophiuroidea (brittle stars). clustered pedicellariae at their bases Contains (conspicuous) madreporite and one row of long thin spine-like Hiebert, T.C. and K. Meyer. 2015. Pisaster brevispinus. 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. A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12923 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to [email protected] adambulacral spines (Fig. 4). A few present in lower reaches of high salinity clusters of pedicellariae occur at the estuarine systems. It is red, brown, or bases of these spines, but there are ochre (juveniles are gray), never pink. It no pedicellariae on the spines (Fisher inhabits only hard substrates (e.g. rocks, 1930; Hyman 1955). pilings), not soft sand. The dorsal spines on Mouth: Large and at center of ventral P. ochraceus form reticulated patterns and surface (Fig. 2). the straight line(s) of spines down each arm Pedicellariae: Two types of that are typical of P. brevispinus are absent pedicellariae on the oral surface: (1) from P. ochraceus. (2) Pisaster giganteus is Small and clustered around bases of bluish gray, with blunt, clubbed dorsal oral spines, and (2) large stalked spines, each surrounded by a ring of blue pedicellariae on bases of flesh around which is a ring of pedicellariae. adambulacral spines (Fig. 4). Pisaster giganteus is a low intertidal sea Tube Feet: Used in locomotion and star, and usually found further south than part of vascular system. Present on Oregon. In spite of its name, it is smaller the ventral side in four rows that are than P. brevispinus when fully grown (Mah staggered down each ambulacral 2007). groove (Fig. 4). Sea stars are extremely variable Ambulacral grooves: Grooves are intra-specifically. Fisher describes two long furrows on oral surface of arms, forms of P. brevispinus (with status currently which contain tube feet and are lined unknown): (1) P. b. brevispinus, from Puget with adambulacral spines (Fig. 4). Sound, Washington to Crescent City, California with an abundance of aboral Possible Misidentifications spines (Fisher 1930). These spines are in Among the large five-armed sea stars, large groups, up to 10 and can form radial Pisaster species are noted for their thick bands; (2) Pisaster brevispinus pacispinus arms, low papillate dorsal spines and has few spines, standing singly or in groups pedicellariae. Pisaster brevispinus is readily of two and three. The spines are usually identifiable by its pink coloration, its stout with subconical acorn-shaped with seemingly soft appearance, and its unusual grooved tips. Papillae (respiratory surfaces) (for sea stars) occurrence on soft are numerous and conspicuous in this form substrates. Two other Asteriidae species (Fig. 3). share these characteristics, but can be differentiated as follows: (1) Evasterias Ecological Information troschelii is slender like P. brevispinus, but Range: Type locality is San Francisco Bay, is generally orange-red or blue-gray (in California (Ahearn 1995). Sitka, Alaska, to Coos Bay), not pink. Its clusters of oral Santa Barbara, California (Fisher 1930). pedicellariae are on the adambulacral Local Distribution: Typically offshore and spines, not just at their bases as in P. on sand bottoms and also found in channel brevispinus (Fig. 4). Like P. brevispinus, E. bottoms of large estuaries, like Coos Bay. troschelii is subtidal (Ricketts and Calvin Habitat: Only in quietest waters and also on 1971; Mah 2007) and its preferred range is wharf pilings and rocks. Cannot tolerate in Puget Sound, Washington, although it is exposure to air or to low salinities for known to northern California. (2) extended periods (Ricketts and Calvin 1971). Orthasterias koehleri has large, sharp Salinity: Collected at salinities around 30. dorsal spines, each surrounded by a distinct Temperature: Cold to temperate. Does not ring of large pedicellariae. These spines tolerate aerial exposure as well as P. are arranged in distinct radial rows and O. ochraceus (Feder 1980). koehleri is often red with yellow mottling Tidal Level: Present in low intertidal, but (Mah 2007). most common subtidally from 0.5–100 m Two other species of Pisaster can (Feder 1980). be found locally: (1) Pisaster ochraceus is a Associates: On low pilings, associates common coastal sea star, and is only include the congener, P. ochraceus, as well Hiebert, T.C. and K. Meyer. 2015. Pisaster brevispinus. 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. as the anemone Metridium, and tunicates, P. ochraceus where development proceeds mussels and barnacles. Several incidences as follows (12˚C): 2 cells at 5hr, 4 cells at of sudden sea star die off have occurred 6hr, 8 cells at 7hr, hatching at 29–32 hr, since 1972, but the most recent to the gastrula at 44–63 hr, planktotrophic bipinnaria northwest coast of North America began in larva at 5d post fertilization (Chia et al. 1987). June 2013 and is called sea star wasting Larva: Embryos develop into planktotrophic disease. Affected individuals have larvae called bipinnariae (Chia et al. 1987; ectodermal lesions and tissue decay that Miller 2001). Bipinnaria larvae are easily eventually leads to death (within 2–3 days). recognizable in the plankton (Fig. 26.1, 26.2, The water-vascular system loses the ability to Chia et al. 1987), they are large, fleshy and maintain hydrostatic pressure and individuals uniformly ciliated with a distinct, continuous often look flaccid when infected. Increased ciliated band that is used for feeding and temperature further heightens infection swimming. They have a large mouth, intensities (Bates et al. 2009). The current esophagus, intestine and anus. They can die off of sea stars is the most significant due have many long arms, increasing in number to its widespread geographic range and large with age and can become long and floppy number of species infected (Hewson et al. (Fig. 3, Miller 2001). The juvenile sea star 2014). Recently, researchers determined this develops from the left posterior portion of the disease is most likely associated with a family larval body. Late stage bipinnaria develop of single stranded DNA viruses (densovirus, three arms (called brachiolar arms) and a Parvoviridae) and is now called sea star- central adhesive disc, anteriorly. Larvae at associated densovirus (SSaDV). Incidentally, this stage are called brachiolaria (see Fig. 4, this same virus was detected in museum Miller 2001) and they use these arm to attach specimens and, thus, may have been present to substratum at metamorphosis.