Squatina californica, commonly known as the Pacific angel shark but also referred to as the "monk fish" or "sand devil" is found in a fairly limited geographical range. Pacific angel sharks inhabit the Eastern Pacific ocean, ranging from Costa Rica to Southern Chile and also from Southeast Alaska to the Gulf of California (Baja), though it is unusual to encounter these sharks north of California between Oregon and Southern Alaska (Smith 2004). The Pacific angel shark is absent along the southern part of Mexico and most of Central America (i.e. Squatina californica is not found south of the Gulf of California or north of Costa Rica) (Bester 2004). (Bester, 2004; Smith, 2004; Troll and Pyles, 2002)
Inhabiting marine temperate and tropical environments, Pacific angel sharks are generally found in shallow waters at depths of 10 to 328 ft (3 to 100 m) off the coast of California but they have also been found as deep as 610 ft (185 m) in the Sea of Cortez (Bester 2004). These bottom-dwelling (benthic) sharks partially bury themselves in sandy or muddy environments during the day (where they may reside camouflaged for weeks until a decent-sized desirable prey enters their domain), while at night they often take a more active approach and cruise over the bottom. This species of shark generally does not move far beyond its chosen territory. These sharks are often found on the continental shelves of western North and South America, in littoral zones, in shallow bays, in sand channels by rocky reefs and outcrops, at the edges of submarine canyons and in kelp forests. (Bester, 2004; Martin, 2003; Nelson, 1994; Smith, 2004)
The Pacific angel shark is a dorsoventrally flattened ray-like shark, with broad, wing-like pectoral fins (which are separated from the head by deep notches) and slightly smaller, wing-like pelvic fins. A terminal mouth is located at the tip of the snout, the eyes and large spiracles are dorsal (on the top of the head), five pairs of gill slits are found from the side of the head to under the throat, and fleshy, nasal barbels and flaps are also located on the head. Pacific angel sharks have two, spineless dorsal fins, no anal fin, and a well-developed caudal fin with a decidedly longer lower lobe than upper lobe (as opposed to the “top-heavy” caudal fin with a longer upper lobe typical of most other sharks). It has been proposed that this tail shape characteristic of Pacific angel sharks is an evolutionary adaptation to the sudden, rapid lift off the bottom they need to ambush and capture unsuspecting prey (Martin 2003).
The ability of Pacific angel sharks to maintain a stationary position on the bottom of the ocean for a sustained period of time is attributed to specific muscles that pump water over the gills and through the spiracles. This feature allows these sharks to breath without having to move through the watery meduim (Monteray Bay Aquarium 2004).
The teeth of Pacific angel sharks are pointed and conical with broad bases, smooth edges, and large gaps at each symphysis. The upper jaw has 9-9 teeth and the lower jaw has 10-10 teeth (Bester 2004).
Pacific angel sharks are typically whitish with red, brown, and grey splotches but certain individuals have been recorded as dark brown to black with blotches of black and brown shades (Bester 2004). The particular coloration of Pacific angel sharks allows them to camouflage themselves with muddy and sandy bottoms.
These sharks do not exceed lengths of 60 in. (152 cm) and weights of 60 lbs. (27 kg) (Bester 2004). Males grow to a maximum length of 118 cm TL while females grow even larger to a maximum length of 152 cm TL (Natanson 1984, cited in Pacific Shark Research Center, 2004). (Bester, 2004; Martin, 2003; Monteray Bay Aquarium, 2004; Natanson, 1984; Nelson, 1994; Pacific Shark Research Center, 2004; Smith, 2004)
Though there is little known about the development and life cycle of Squatina californica, it has been observed that males grow and reach maturity at a length of 30 to 31 in. (75 to 80 cm) and an age of 8 years whereas females develop and reach maturity at a length of 35 to 39 in. (90 to 100 cm) and the age of 13 years. (Bester, 2004)
We have no information about the mating systems of the Pacific angel shark.
The reproductive cycle of the Pacific angel shark is typically annual (the fecundity ranges from approximately 1 to 10 ovarian eggs produced with an average of 7) with a gestation period of approximately 10 months and the births occurring primarily between March and June in the northern part of the species' range (Natanson and Cailliet 1986, cited in Pacific Shark Research Center, 2004). Pacific angel sharks reproduce by aplacental vivipary (ovovivipary), which means that the eggs hatch inside of the mother’s body and there is no nourishing placenta to sustain the young. Instead, nutrition is provided by an external yolk which shrinks as the pups grow and shifts into an internal sac when the embryo reaches 150 mm TL. The stored yolk is then transferred from the internal sac to the intestine of the embryo where is it absorbed (Bester 2004). Though the litter size can range from 1 to 13, the number of pups per pregnancy is generally between 8 and 13. At birth, the pups are on average, 9 in. (23 cm) long. Males tend to reach sexual maturity earlier than females at the age of 8 years, while females reach sexual maturity around the age of 13 years (Bester 2004). (Bester, 2004; Hamlett, 1999; Martin, 2003; Natanson and Cailliet, 1986; Pacific Shark Research Center, 2004)
Little has been recorded regarding parental investment in Pacific angel sharks but the long gestation period (approx. 10 months) and the development of the embryo inside the mother’s body indicate that a significant amount of time and energy is invested in ensuring the growth and immediate survival of the young pups. There is no known dependence of the pups on their parents: once the pups are born they are on their own. (Bester, 2004; Hamlett, 1999)
The maximum reported age of a Pacific angel shark is 35 years (Natanson 1984, cited in Pacific Shark Research Center 2004). (Natanson, 1984; Pacific Shark Research Center, 2004)
Pacific angel sharks are most commonly found alone but they may occasionally be spotted in aggregations. Adult Pacific angel sharks are considered semi-nomadic, and have been observed to spend several days in one location and then move to another. Off Catalina Island, California, tagged individuals showed great variation in mobility. Some remained sedentary for years, others migrated seasonally (Martin 2003). They spend the daylight hours waiting on the seafloor for suitable prey, moving only to quickly ambush attack their source of food. At night, Pacific angel sharks actively forage for food, with sonic telemetry revealing a notable increase in physical activity at sundown which reaches a climax around midnight (Martin 2003). It has been observed that Pacific angel sharks will strategically choose ambush sites based on previous or potential hunting success (Ebert 2003, cited in Pacific Shark Research Center, 2004). (Bester, 2004; Ebert, 2003; Fouts and Nelson, 1999; Martin, 2003; Pacific Shark Research Center, 2004)
There is little known about communication and perception among Pacific angel sharks. Squatina californica principally utilizes its eyes (on the top of the head) and sense of feel while it camly lies in wait at the bottom of the sea floor for prey. These sharks are known to be electroreceptive, utilizing electric fields to locate prey. While many species of sharks must move/swim in order to breath, Pacific angel sharks have muscles that pump water over the gills and through the spiracles so that it is not necessary for them to move, an adaptation crucial to their ambush style of feeding. (Monteray Bay Aquarium, 2004)
Pacific angel sharks are carnivores that primarily feed on bony fish and cephalopods (squid and octopus) but are known to consume crustaceans and other types of mollusks as well. Of the bony fish, Pacific angel sharks attack croakers (Scianidae, Atractoscion nobilis and Seriphus politus); flatfish (Pleuronectiformes); corbina (Menticirrhus undulatus); sea basses (Serranidae, Paralabrax clathratus); blacksmith (Pomacentridae, Chromis punctipinnis); mackerels, tunas, and bonitos (Scombridae); hake and halibut (Hippoglossus stenolepis); Pacific sardines (Clupeidae, Sardinops sagax) and also peppered shark (Galeus piperatus)(Fouts and Nelson 1999 and Ebert 2003, cited in Pacific Shark Research Center, 2004; Martin 2003). (Bester, 2004; Ebert, 2003; Fouts and Nelson, 1999; Martin, 2003; Pacific Shark Research Center, 2004)
Pacific angel sharks are only preyed upon by some larger sharks, including white sharks (Carcharodon carcharias) (Bester 2004; Ebert 2003, cited in Pacific Shark Research Center, 2004). Humans, through the booming trawl and gillnet fishery in the early 1980’s, also posed a threat to the survival of Pacific angel sharks. Many of these fisheries are now either regulated or closed in order for the depleted population of Pacific angel sharks to increase again. (Bester, 2004; Ebert, 2003; Pacific Shark Research Center, 2004)
Pacific angel sharks are predators that eat a variety of other smaller marine predators. They are, in return, preyed upon by bigger sharks. Parasites associated with Squatina californica include tapeworms (1 family, 1 species), flukes (1 family, 1 sp.), marine leeches (1 family, 1 sp.), and protozoans (1 family, 1 sp.) (Love and Moser 1983, cited in Pacific Shark Research Center, 2004). (Bester, 2004; Cortés, 1999; Love and Moser, 1983; Pacific Shark Research Center, 2004)
Until the late 1970’s Pacific angel sharks were not marketed. In 1978, the trawl and gillnet fisheries off the California coast expanded and Pacific angel sharks, caught both commercially by the fisheries and recreationally by divers and sportfishers, became an important shark food for human consumption. Primarily during the early and mid 1980’s, the abundant Pacific angel shark flesh was both frozen and marketed fresh for humans to enjoy. (Bester, 2004; Martin, 2003)
Since Pacific angel sharks spend most of their time buried in sand or mud at the bottom of estuaries, bays or the ocean where they reside, these sharks are considered relatively peaceful if left alone. But if these sharks are provoked (by being trodden on, pulled by the tail, approached head on, captured, etc.) their extremely sharp teeth and aggressive bite can inflict severe and painful lacerations. Consequently, close encounters with these sharks can often adversely affect human health and safety. (Bester, 2004; Martin, 2003)
Due to the large regulated trawl and gillnet fishery off the California coast, which was primarily instituted by Santa Barbara fish processor Michael Wagner in 1978, the number of Pacific angel sharks significantly decreased (Martin 2003). Landings for Pacific angel sharks jumped from 366 lbs. in 1977 to more than 700,000 lbs. in 1984. It became the leading shark food from 1985 to 1986 until size limits were imposed and near shore fishing (i.e. gillnetting inshore of 3 miles) was banned by a voter initiative (Smith 2004). The gillnet fisheries of California are now closed because of the severely depleted populations of Pacific angel sharks. Renewal of gillnetting could potentially threaten the future survival of Pacific angel sharks off of the U.S. coast. The IUCN red list currently indicates that Squatina californica is tagged as “Near Threatened” (LR/nt). (Bester, 2004; Martin, 2003; Smith, 2004; Troll and Pyles, 2002)
Squatina californica, commonly known as the Pacific angel shark, was described in 1859 by the first curator of Icthyology at the California Academy of Sciences: William O. Ayres. (Bester, 2004)
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Leanne De Craene (author), University of Michigan-Ann Arbor, William Fink (editor, instructor), University of Michigan-Ann Arbor.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
the nearshore aquatic habitats near a coast, or shoreline.
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
uses electric signals to communicate
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
parental care is carried out by females
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
fertilization takes place within the female's body
the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
makes seasonal movements between breeding and wintering grounds
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.
an animal that mainly eats fish
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
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