This week’s featured species is an actual flat shark species from the eastern Pacific Ocean. The Pacific Angelshark (Squatina californica), sometimes referred to as the California Angelshark, is a species of shark that is often mistaken for a stingray. They have dorso-ventrally flattened bodies, with broad, long, pectoral fins that sit high up behind their heads (Ebert, Fowler, & Dando, 2015). The strange shape created by their heads and pectoral fins was thought to resemble a monk’s cloak and so angelsharks were once called monkfish (Parker, 2008). The adults are speckled with light spots and dark splotches and have a distinct white edge along the pectoral and pelvic fins (Ebert, Fowler, & Dando, 2015). These irregular markings help the Pacific angelshark virtually disappear beneath soft, sandy and muddy substrates while they wait to ambush their prey.
The Pacific angelshark is a master of disguise. With their speckled, flattened bodies, they snuggle themselves beneath a soft substrate and virtually disappear. The Pacific angelshark can remain nearly motionless for hours under the sand as they wait for small fishes to swim over head. The Pacific angelshark strikes out at its prey by rapidly expanding its branchial, or gill, chamber as it opens its mouth. This creates negative pressure, drawing its prey directly into its mouth (Klimley, 2013). This style of ambush predation is common among dorso-ventrally compressed angelsharks in Squantiniformes, the wobbegongs of Orectolobidae, and the skates of Rajiformes (Klimley, 2013).
The Pacific angelshark feeds on bony fishes like flatfish, halibut, croakers, and peppered shark, and is even known to consume some invertebrates like crustaceans and mollusks. The angelshark has an impressive set of jaws that are perfectly adapted to ambush their prey. Their teeth are pointed and conical, or cone shaped (Fouts & Nelson, 1999). They have smooth edges with broad bases. The teeth are angled slightly towards the back of the jaw to hook and hold prey in the mouth. Once a fish enters, there’s no coming out.
The Pacific angelshark, like many species of elasmobranch, is slow to reach sexual maturity. On average, it takes 8 to 13 years before a Pacific angelshark will be ready to reproduce (Cailliet, Mollet, Pittenger, Bedford, & Natanson, 1992; Cortés, 2002). Pacific angelsharks reproduce via aplacental viviparity, also known as ovoviviparity. This means that the pups develop within the mother’s womb, but are not attached to the mother. Instead, each pup has its own yolk sac that contains the nutrients it will need while developing over its 10 month gestation period (Natanson, & Cailliet, 1986; Ebert, 2001). Pupping occurs in spring from March to June. The video below is from an endoscopy of the womb of a pregnant angelshark. It’s a unique glimpse at developing angelshark pups!
ODN (Videographer). (2011). Footage of Angelshark pups inside their pregnant mother [Video Clip]. Retrieved from https://www.youtube.com/watch?v=kC3mWgNU4cY
The Pacific angelshark is found along the western coast of North America from Alaska to Baja, Mexico. During the day, they prefer to settle into areas near reefs populated with small fishes where they can settle into a soft bottom substrate and ambush them (Klimley, 2013). Under the cover of darkness, they have been observed to migrate to other hunting grounds (Klimley, 2013). However, the Pacific angelshark is not known to make large migrations. They are a fairly residential species, restricting their movements to small geographic areas, typically less than 0.5 square miles (1.29 square km) (Ebert, 2003; Love, 2011). However, one shark tagged in Catalina Island was recaptured 3.5 years later in Santa Cruz Island, over 60 miles (100 km) away (Leet, 2001)!
During the 1970’s, the Pacific angelshark was commercially harvested by the fisheries industry (Cailliet, Chabot, Nehmens, & Carlisle, 2016). In 1977, landings of the Pacific angelshark totaled 0.15 metric tonnes (mt). In 1987, landings peaked at 426 mt. By 1991, landings had declined to 112 mt (Cailliet, Chabot, Nehmens, & Carlisle, 2016). The declines in landings were not entirely related to population decline, though that was a factor. In 1991, California also banned the use of gill and trammel nets, leading to dramatic decreases bycatch from the California halibut (Paralichthys californicus) industry. Between 2005 and 2014, landings stabilized to range from 4.04 to 6.81 mt per year (Cailliet, Chabot, Nehmens, & Carlisle, 2016). Today, the Pacific angelshark is categorized by the International Union for the Conservation of Nature (IUCN) as Near Threatened. Within Washington, Oregon, and California, the Pacific angelshark is managed under the Groundfish Fishery Management Plan. Beginning in 2012, Mexico issued a seasonal fishing closure from May 31st to July 31st to all fisheries targeting elasmobranchs (Cailliet, Chabot, Nehmens, & Carlisle, 2016).
Authority: Ayres, 1859
Family: Squatinidae; 20 species described, others have not yet been described and named
Length: Females reach a maximum of 5.7 feet (1.75 m); males reach a maximum of 3.9 feet (1.2 m)
Weight: 60 lbs (27 kg)
Habitat: Continental shelves, rocks, and kelp beds with soft bottom substrates
Depth: Surface to 330 feet (100 m)
Gestation: 10 months
Litter Range: 1 – 13 pups
Home Range: Northeastern Pacific Ocean along the western coast of North America, ranging from Baja, Mexico to Alaska
Diet: Small bony fish and invertebrates
IUCN Status: Near Threatened
(Ebert, Fowler, & Dando, 2015; Cailliet, Chabot, Nehmens, & Carlisle, 2016)
The new Ocean For Sharks Shop is open! There’s handmade ocean inspired plush animals, canvas paintings, and of course my children’s book, Winifred the Wondrous Whale Shark, available in print and PDF. Be sure to stop by. Remember proceeds benefit shark research and conservation with a donation to Project AWARE!
Thanks so much for checking out the beautiful Pacific Angelshark! If you missed last week’s featured species, please be sure to check out the Pelagic Thresher Shark! If there is a species of elasmobranch you’d love to know more about, leave me a comment or send me a message! I would love to do a feature on your favorite species. So connect with me on Instagram and Facebook for even more elasmo fun!
Conservation legislation needs public support in order to become law and help protect the environment and wildlife. Tell your representatives that you care about environmental and wildlife conservation. It only takes a moment to make a change that will last a lifetime. Until next time finactics!
Featured Image Source
Cailliet, G. M., Mollet, H. F., Pittenger, G. G., Bedford, D., & Natanson, L. J. (1992). Growth and demography of the Pacific angle shark (Squatina californica), based upon tag returns off California. Marine and Freshwater Research, 43(5), 1313-1330.
Cailliet, G.M., Chabot, C.L., Nehmens, M.C. & Carlisle, A.B. (2016). Squatina californica. The IUCN Red List of Threatened Species. Retrieved from https://www.iucnredlist.org/species/39328/80671059
Cortés, E. (2002). Incorporating uncertainty into demographic modeling: application to shark populations and their conservation. Conservation biology, 16(4), 1048-1062.
Ebert, D. A. (2003). Sharks, Rays, and Chimaeras of California University of California Press. Berkeley, California.
Ebert, D. A., Fowler, S. L., & Dando, M. (2015). Sharks of the world: a fully illustrated guide. Wild Nature Press.
Fouts, W. R., & Nelson, D. R. (1999). Prey capture by the Pacific angel shark, Squatina californica: visually mediated strikes and ambush-site characteristics. Copeia, 304-312.
Klimley, A. P. (2013). The biology of sharks and rays. University of Chicago Press.
Leet, W. S. (2001). California’s living marine resources: a status report. University Of California, Division of Agriculture and Natural Resources; Califorinia Sea Grant.
Love, M. S. (2011). Certainly more than you want to know about the fishes of the Pacific Coast: a postmodern experience. Really Big Press.
Natanson, L. J., & Cailliet, G. M. (1986). Reproduction and development of the Pacific angel shark, Squatina californica, off Santa Barbara, California. Copeia, 987-994.
Parker, S. (2008). The encyclopedia of sharks (2nd ed.). Buffalo, NY: Firefly Books Ltd.