Phylum: Chordata Chely osoma columbianum Class: Order: Flat-topped Family:

Carmen ReddickS

Taxonomy: columbianum was Possible Misidentifications originally described by Huntsman in 1912. Chelyosoma productum can be found in the The only synonym is Chelyosoma same region as C. columbianum. The two columbiana, a literature misspelling (Shenkar can be distinguished by the et al. 2020b). appearance of their test and disk. Chelyosoma columbianum is the smaller of Description the two species (Huntsman 1912) and has a Size: The distance between an individual’s very flat disk and a low profile, with its height two siphons is up to 19 mm in length and typically much smaller than its width. perpendicularly its width is up to 14 mm. Chelyosoma productum is significantly taller, Color: Yellowish hue and often clear or with a width to height ratio of about 1:1. transparent (Van Name 1945). Chelyosoma productum also lacks the visible General Morphology: Smooth, sac-like, short muscle strands found in C. elliptical-shaped test protecting internal parts columbianum (Van Name 1945). (Van Name 1945). Test and Disk: Test is not a true part of the Ecological Information body, as it is a secretion of mantle and the Range: Originally discovered in Departure body can be completely removed from it. Bay and Burrard Inlet, British Columbia Asymmetrical, flat-topped disk created by test (Huntsman 1912). Now known to inhabit the (Van Name 1945). North Pacific from to Columbia Siphons: Branchial and atrial siphons. (Shenkar et al. 2020b). Siphonal plates are at the same level as the Local Distribution: Found near Stonewall disk (Van Name 1945). Bank offshore of Newport, . Full local Plates: Number of plates may differ among distribution is unknown and occasionally on individuals, but there are generally two central cobbles off Cape Arago. plates, two intermediate, and 12 marginal Habitat: Rocky and shell hash sea floor plates found level to the disk. (Van Name (Huntsman 1912). 1945). Temperature: Identified in Stonewall Bank Musculature: Siphonal and marginal where sea temperatures range from 6.6 °C to muscles, as well as distinguishable short 22.3 °C (NDBC 2009). muscle strands that cross all the lines located Depth: Found between 18 and 313 meters away from the margin (Van Name 1945). (Van Name 1945). Internal Parts: Inside the test’s protective Associates: Lives in association with layer is the mantle, another sac-like coralline algae, the vase sponge membrane (Van Name 1945). This species is Aphrocallistes vastus, the Anthozoan known to have between 50 and 100 tentacles, Pachycerianthus fimbriatus, the Bryozoan 12 to 22 languets, and 33 to 42 bars on each Cellaria sp., the brachiopods Crania side of its pharynx. Stigmata are coiled with a californica and Laqueus californianus, the sea maximum of 2.5 turns. Gastric folds run star Stylasterias forreri, and other vertically, intestine is narrow, and dorsal including Bathypera feminalba, Boltenia tubercle is transverse. Loop is narrow and polyplacoderma, and igaboja, located to the right posterior side (Huntsman and Rhopalea cloneyi. (Vàzquez and Young 1912). 1996). Abundance: Likely uncommon (Van Name 1945) but common on walls of Saanich Inlet

Reddick, C. 2021. Chelyosoma columbianum. In: Oregon Shelf Invertebrates. C.Q. Plowman and C.M. Young (eds.). Oregon Institute of Marine Biology, Charleston, OR. and Barkley Sound (C.M. Young, personal 46050. Accessed at: communication). https://www.ndbc.noaa.gov/data/climat ic/46050.txt Life-History Information: 4. SHENKAR, N., A. GITTENBERGER, Little is known specifically about the G. LAMBERT, M. RIUS, R. MOREIRA reproduction, larval and juvenile stages, da ROCHA, B. J. SWALLA, and X. predators, and behavior of C. columbianum, TURON. 2020a. Chelyosoma therefore these categories will detail columbianum Huntsman, 1912. information known about the shallow-water Accessed at congener C. productum. http://www.marinespecies.org/ascidiac Reproduction: All solitary ascidians are ea on 2020-07-12. doi:10.14284/353 hermaphrodites and most phlebobranch 5. SHENKAR, N., A. GITTENBERGER, ascidians are capable of self-fertilization. In C. G. LAMBERT, M. RIUS, R. MOREIRA productum, gametes are released after da ROCHA, B. J. SWALLA, B.J. and sunrise in response to light (Young and X. TURON. 2020b. Ascidiacea World Braithwaite 1980). Database. Chelyosoma Larva: Tadpoles of this species have not columbianum Huntsman, 1912. been described, but it expected that they Accessed through: World Register of swim for no more than a few days, like those Marine Species at: of related phlebobranchs (Cloney, Young, and http://www.marinespecies.org/aphia.p Svane 2003) hp?p=taxdetails&id=250009 on 2020- Juvenile: Juveniles of Chelyosoma 07-12 productum have been described by Young 6. STOECKER, D. 1980. Chemical and Braithwaite 1980. In this species, juvenile Defenses of Ascidians Against form depends on the proximity of neighboring Predators. Ecology. 61:1327. conspecifics; crowded individuals develop a 7. VAN NAME, W. G. 1945. The North long epidermal ampulla. and South American Ascidians. Longevity: Unknown Bulletin of the American Museum of Growth Rate: Unknown Natural History. 84:11-19, 208-209. Food: Filter feeds on small (Van 8. VÀZQUEZ, E., and C. M. YOUNG. Name 1945). 1996. Rhopalaea cloneyi (Ascidiacea, Predators: Unknown. Other plebobranch Cionidae), a new deep-water ascidian ascidians in the same region are preyed upon from the coastal waters of British by the gastropod oregonensis Columbia. Journal of Zoology, (Young 1985). Chelyosoma productum are 238(4):606. capable of cannibalizing their own larvae 9. YOUNG, C.M. and L. F. (Young 1988). BRAITHWAITE. 1980. Larval Behavior Behavior: Unknown and Post-settling Morphology in the Ascidian, Chelyosoma Productum. Bibliography Journal of Experimental Marine Biology and Ecology. 42:157-169. 1. CLONEY, R. A., C. M. YOUNG, and I. 10. YOUNG, C.M. 1985. Abundance SVANE. 2006. Phylum Chordata: patterns of subtidal solitary ascidians Urochorda, p.565-571. In: Atlas of in the San Juan Islands, Washington, Marine Invertebrate Larvae. C.M. as influenced by food preferences of Young (ed.). the predatory snail Fusitriton 2. HUNTSMAN, A. G. 1912. Ascidians oregonensis. Marine Biology from the coasts of Canada. 84:309-321. Transactions of the Royal Canadian 11. YOUNG, C.M. 1988. Ascidian Institute 9:124. cannibalism correlates with larval 3. NDBC. 2009. Monthly and Annual behavior and adult distribution. Journal Frequency and Cumulative Percent of Experimental Marine Biology and Frequency: Sea Temperature. Station: Ecology 117:9-26. A publication of the Oregon Institute of Marine Biology at the University of Oregon. https://oimb.uoregon.edu/oregon-shelf-invertebrates Email corrections to: [email protected]

Figure 1. Sessile adult C. columbianum with a yellowish, transparent test permanently attached to a rock. Individual was collected from 120 m near Stonewall Bank offshore of Oregon in September 2019. Photograph by M. Hainey.

Reddick, C. 2021. Chelyosoma columbianum. In: Oregon Shelf Invertebrates. C.Q. Plowman and C.M. Young (eds.). Oregon Institute of Marine Biology, Charleston, OR.