The Pacific angelshark (Squatina californica) is a species of shark belonging to the family Squatinidae, found in the eastern Pacific Ocean. The Pacific angelshark inhabits shallow, coastal waters on sandy flats, usually near rocky reefs and even kelp forests. They have a flattened body and greatly enlarged pectoral and pelvic fins. They have extremely unique and beautiful coloring with patterns disguising them perfectly with their surroundings. These sharks individually choose ambush sites and remain there for a few days before finding a new one. They are much more active at night.
Family: Squatinidae – Angel Sharks
Genus: Squatina
Species: californica
Phylum– Chordata
Class– Chondrichthyles
Subclass– Elasmobranchii
Infraclass– Euselachii
Superorder– Selachimorpha
Common Name– Angel Sharks or Angelsharks
Family– Squatinidae
Common Name– Angel Sharks or Angelsharks
Genus– Squatina
Species– californica
Status: IUCN Red List NEAR THREATENED
Average Size and Length: They are born between 25-26 cm/9.8-10.2 inches. Mature sharks have been measured around 100 cm/ 3.3 feet. The maximum length is between 120-152 cm/ 3.9-5 feet. The Mexican population is smaller in size.
Average Weight: One subject weighed 60 pounds.
Current Rare Mythical Sightings: The Pacific angelshark was first scientifically described in 1859 by William Orville Ayres, the first Curator of Ichthyology at the California Academy of Sciences. Locally, they may also be referred to as Angel shark, California Angel shark, or Monkfish. There are other species that are very closely related that were tough to be the same species in the past.
Teeth and Jaw: The mouth is very wide and placed terminally. They have expendable necks and trap-like jaws that can rapidly snap upwards and hinge shut. They have long, needle-like teeth in the upper and in the lower jaws used for gripping. There are 9 tooth rows on either side of the upper jaw and 10 tooth rows on either side of the lower jaw, with toothless gaps at the middle of both jaws. Each tooth has a broad base and a single narrow, smooth-edged cusp.
Head: There are conical nasal barbels with spatulate or spoon-like tips. There are weakly fringed anterior nasal flaps. There are no triangular lobes on the lateral head folds. The eyes are located on top of the head, with the spiracles behind. The area between the eyes is concave. The eye to spiracle space is less than 1.5 times the eye length.
Denticles: There are thorns prominent in young. They are small or not there at all in adults.
Tail: The lower lobe of the caudal fin is larger than the upper, but only very slightly, and almost unnoticeable.
Demographic, Distribution, Habitat, Environment and Range: The Pacific angelshark can be found in the northeast Pacific Ocean, and possibly the southeast Pacific Ocean. They have been found from Alaska to the Gulf of California, and from Ecuador to Chile, although those in the Gulf of California and southeastern Pacific may in fact be separate species. They can be found on the continental shelf between 5-673 feet. They are found near rocks and sometimes found near kelp. They prefer cold to warm-temperate waters.
Diet: They feed mainly on bony fishes, including kelp bass, croakers, flatfishes, damselfishes, mackerels, and sardines. During the winter and early spring, spawning squid are abundant and become their primary source of food. In other species groups in other locations, the primary fish may vary.
Large sharks, including the Great White shark, the Broadnose Sevengill shark, and even the northern Elephant seal are known to consume Pacific angelsharks.
Ram-Suction Index: They have an RSI more towards the suction end of the scale. They lay flat and still on the bottom, when the time comes, they lung at prey and suck it into their mouths with negative pressure.
Fouts and team describe the striking action of the Pacific angelshark. The shark presses the forward lobes of its pectoral fins against the bottom and thrusts its head upwards at up to a 90° angle. Its mouth forms a tube when opened, creating a suction force, while its jaws protrude forward to secure the prey between sharp teeth. During the strike, the eyes roll backward into the head for protection. The strike is often completed in under a tenth of a second.
Aesthetic Identification: The Pacific angelshark is reddish-brown to dark brown or even blackish. There are scattered light spots, which are set around dark blotches in adults. There are large paired dark blotches on the back and the tail to form large ocelli in young sharks. The pectoral and pelvic fins have white edges. There are pale dorsal fins with dark blotches at the base. There is a dark spot at the base of a pale, spotted tail. The 5 pairs of gill slits are located on the sides of the head. They have a flattened body and greatly enlarged, angular pectoral and pelvic fins with pointed tips. There are long, broad and high pectoral fins. The expanded anterior lobes of its pectoral fins are separate rather than fused to the head. The two dorsal fins are located far back on the body, and there is no anal fin.
Biology and Reproduction: They are ovoviviparous having 6-10 pups per litter after a gestation period of between 9-10 months. Off Santa Barbara, birthing takes place from March to June. The pups are born in water between 180–295 feet deep. Pacific angelshark embryos grow at 1.8 inches per month when young, slowing down to 0.39 inches per month just before birth, and are born at a length of 9.8–10.2 inches. Newborn pups in captivity grow at a rate of around 5.5 inches per year, while adults in the wild grow at around 0.79 inches per year. Both sexes mature at 3.0–3.3 feet long. (Natanson, L.J. & Cailliet, G.M. (December 23, 1986). “Reproduction and Development of the Pacific Angel Shark, Squatina californica, off Santa Barbara, California“. Copeia. 1986 (4): 987–994).
About 20% survive to maturity at between 10-13 years old. The maximum lifespan has been estimated at 25–35 years, however age verification by vertebra is difficult in the Pacific angelshark. The reason why is because the growth rings on the vertebrae of Pacific angelsharks are deposited in proportion to the shark’s size rather than yearly.
Known parasites include the copepod Trebius latifurcatus, which infests the skin, the myxosporidian Chloromyxum levigatum, which infests the gall bladder, and the tapeworm Paraberrapex manifestus, which infests the spiral valve intestine. The leech Branchellion lobata may be attached around this shark’s cloaca, inside the intestine, and even inside the uterus and on developing embryos. (Jameson, A.P. (December 1931). “Notes on Californian Myxosporidia“. The Journal of Parasitology. The American Society of Parasitologists. 18 (2): 59–68.) (Moser, M. & Anderson, S. (1977). “An intrauterine leech infection: Branchellion lobata Moore, 1952 (Piscicolidae) in the Pacific angel shark (Squatina californica) from California“. Canadian Journal of Zoology. 55 (4): 759–760.)
A phylogenetic study based on mitochondrial DNA, published by Björn Stelbrink and colleagues in 2010, reported that the sister species of the Pacific angelshark is the Sand Devil (S. dumeril). The two species are estimated to have diverged approximately 6.1 Ma, close to when the Isthmus of Panama first began to form. They are individual species though. (Stelbrink, B.; T. von Rintelen; G. Cliff & J. Kriwet (2010). “Molecular systematics and global phylogeography of angel sharks (genus Squatina)”. Molecular Phylogenetics and Evolution. 54 (2): 395–404.)
A number of genetically discrete subpopulations have been identified across the northern range of the Pacific angelshark. Several subpopulations exist along the coast from Point Conception northward to Alaska. In the Southern California Bight, there are at least three separate subpopulations off the mainland and northern and southern Channel Islands. The subpopulation along the Pacific coast of Baja California are distinct from those in the Gulf of California. These subpopulations have diverged from one another over time because Pacific angelsharks do not undertake long migratory movements outside of their preferred home areas, and deep waters serve as effective geographical barriers to population mixing. Heterozygosity, a measure of genetic diversity, is higher in the Pacific angelshark than in other shark species that have been examined. (Gaida, I.H. (December 9, 1997). “Population Structure of the Pacific Angel Shark, Squatina californica (Squatiniformes: Squatinidae), around the California Channel Islands“. Copeia. American Society of Ichthyologists and Herpetologists. 1997 (4): 738–744.)
Behavioral Traits, Sensing and Intelligence: The Pacific angelshark lies buried still in the mud or in the sand during the day waiting to ambush prey. They are actively swimming during the night. Individual sharks actively choose ideal ambush sites, where they stay for several days before moving on to a new one. The prey learns to avoid the areas. They do not swim long distances. Individual sharks choose sites giving them the best ambush success. They prefer junctions of sandy and rocky substrates near reefs (used by many fishes for shelter) usually orienting themselves either toward or parallel to nearby vertical structures. They tend to face upslope, which may facilitate burying via falling sediment, bring more fish swimming downstream from the reef, or ease targeting by silhouetting prey against the sunlight. One study off Santa Catalina Island found that over 13–25 hours, nine sharks together used only 1.5 km2 (0.6 mi2). A later, longer-term study found that the sharks’ sporadic position changes covered as much as 75 km (47 mi) over three months, almost circling the island. Single individuals swam up to 7.3 km (4.5 mi) in a night. (Fouts, W.R. & Nelson, D.R. (May 7, 1999). “Prey Capture by the Pacific Angel Shark, Squatina californica: Visually Mediated Strikes and Ambush-Site Characteristics“. Copeia. American Society of Ichthyologists and Herpetologists. 1999 (2): 304–312.)
Pacific angelsharks have a unique way of breathing compared to most other benthic sharks and fish. They do not pump out water from the oropharyngeal cavity. Instead, they use gill flaps located on the sides of their body to pump out water during respiration. Doing so also allows them to be more unnoticeable and prevent detection from unwanted predators.
Pacific angelsharks rely heavily on their vision to strike at prey. They focus on striking directly from the front, 5.9 inches away. The greater the distance, the less accuracy. Some research in the field exhibits that they strike at fish-shaped targets without any electrical, chemical, vibrational, or behavioral cues. At night, they are guided by the bioluminescence of planktonic dinoflagellates and ostracods disturbed by moving prey. (Martin, R.A. Sandy Plains: Pacific Angel Shark.)
Pacific Angelshark Future and Conservation: They are near threatened. They were abundant in California until commercial fishing depleted their population in the 1990’s. Their meat and skin are valued highly. The gill net ban (which started in 1976) ended the fishing in 1994. The fishery peaked in 1985 and 1986, when 1.2 million pounds were taken annually, making this species the number one shark fished off California. This level of exploitation was unsustainable, and despite a minimum size limit imposed in 1986, catches fell to 247,000 pounds in 1990. They are taken as bycatch. They are important, and subject to dive tourism in California. They are now mainly fished in Mexican waters.
Pacific Angelshark Recorded Attacks on Humans: Pacific angelsharks aren’t dangerous to humans unless provoked. Because of their powerful jaws and sharp teeth, they can inflict injury on anyone or anything that may pose a threat to them. There have been cases of Angel sharks biting divers that have tried to restrain them, approach too close to the head, corner them, or grab their tails.