Horn Shark
Heterodontus francisci
Horn sharks are small sharks that prefer shallow waters, and often shuffle along on their pectoral fins instead of swimming seamlessly like many of their larger kin. Horn sharks prefer to stay in their own territory in shallow waters rather than venturing out into new or deeper areas.
The eggs of these sharks are shaped like corkscrews, which moms wedge into crevices in their habitats. This helps the eggs stay put during the six to nine-month growth period. That way, the egg won’t float away — when the baby horn sharks hatch, they will be in a sheltered environment with plenty of food available to them!
Credit: Ken Kurtis
SPECIES IN DETAIL
Horn Shark
Heterodontus francisci
CONSERVATION STATUS: Data deficient
CLIMATE CHANGE:
At the Aquarium
Blue Cavern, Casino Point
Geographic Distribution
Southern California and the Channel Islands to the Gulf of California and Baja California
Habitat
Horn sharks rarely swim more than two meters (about six feet) above the substrate, tending to stick to depths between two and 11 meters (between six and 36 feet). When they’re younger, they usually stick to depths shallower than 10 meters (about 33 feet). They go a little bit deeper as they get older (but not much). Occasionally, these sharks have been spotted as deep as 150 meters (492 feet).
Physical Characteristics
These sharks have a very distinctive appearance. They have high ridges above their eyes, topping off a blunt, short head. They range from various shades of gray or muddy brown with dark brown or black spots, with spines on their dorsal fins and anal fin. (These spines are where their “horn” moniker comes from.) Their dorsal fins are very broad and muscular, spanning a larger portion of their body than other sharks — they can use these fins to help them crawl along the ocean bottom.
Size
Up to a little over a meter long (about 4 feet).
Diet
These sharks are pretty inactive during the daytime, emerging at night in search of food. While they shelter in shallow rocky crevices while resting, they venture out over sandy flats, eelgrass beds, and muddy terrain to seek their meals at night, which consist largely of crustaceans, cephalopods, small fishes, lobsters, and sea urchins.
When they capture their prey, they have help from their “different teeth.” Heterodontus, their scientific name, means exactly that. It’s important because their front teeth are sharp to grasp their slippery food (cephalopods and fishes), while their back teeth are more like molars — flat — to help them crush the crustaceans and sea urchins that make up so much of their diet.
Reproduction
Horn shark eggs are quite unique, forming a corkscrew shape rather than the more traditional “mermaid’s purse” flat rectangular shape of other shark eggs. This corkscrew shape is very important, as it is meant to be wedged into the crevices where horn sharks spend most of their time. During the six to nine months it takes the eggs to hatch, they are more likely to remain in the place where they will have shelter and food upon hatching, rather than floating away to an unsuitable habitat.
The shape of the horn shark egg doesn’t make it completely different from other shark eggs, though. The hatching sharks still exit the egg through the side with the wider seam. The opposite end is also still narrower where it would have emerged first from the parent. Like other shark eggs, horn shark eggs also have lateral keels (a flexible structure to help anchor the egg to the ocean floor) and tendrils (a long sticky substance that also helps the egg anchor to the substrate).
Behavior
These sharks are not the traveling type. Prone to what’s called high site fidelity, or sticking to one area consistently, horn sharks generally return to the same home and feeding grounds time and again. They seem to have somewhat distinct populations between islands and mainland habitats, suggesting that they prefer not to cross open water to travel.
Instead, horn sharks tend to stick to the shallow waters more readily available to them. This is fairly unique in sharks, who tend to disperse more widely, at least for reproductive purposes. Because of their tendency to stick very close to home, it may be even more important to gather more data about horn shark population levels to ensure that they remain protected in a changing ocean climate.
Before these sharks mature, they seem to spend most of their time in very shallow, warmer waters — less than about 10 meters (30 feet) of depth. As they mature and grow larger, they shift to cooler, deeper waters (more than 10 meters depth), taking refuge in bigger caves and rock ledges instead of the small crevices and overhangs of their youth.
Adaptation
Horn sharks are nocturnal, meaning that they are mostly active at night, preferring to hide and rest during the day. And even though they are well adapted with camouflage from their typically brown color patterns and darker spots, at least one horn shark with leucism — a lack of pigmentation resulting in a lot of white skin — has been documented as surviving quite well in La Jolla for several years. This suggests that their hiding skills and high site fidelity may help them survive as effectively as camouflage.
Longevity
Horn sharks are thought to live up until around 25 years old.
Conservation
The IUCN has listed their conservation status as Data Deficient. Data may be hard to come by because these sharks are with high site fidelity — they largely stick to the same places over time — and because their range is relatively small, just up the coast from the Gulf of Mexico in Mexico through southern California and the Channel Islands.
However, along this range, at least one study has identified horn sharks as being potentially vulnerable to overexploitation, particularly due to the impacts of becoming bycatch and the practices of artisanal fisheries. The study notes that the low economic value of certain species — due in part to horn sharks not being directly targeted for fishing — means that data about these species and subsequent protective measures are less readily available.
Studies have also shown that horn sharks have metabolisms that are relatively sensitive to temperature change. This may be especially true for juveniles, who seem to require a very specific, stable temperature. This temperature sensitivity implies that warming oceans may negatively impact horn sharks.
Special Notes
These sharks can crawl along the bottom of the ocean floor with their broad, muscular pectoral fins. The corkscrew shape of horn shark eggs allows them to get wedged into crevices, keeping them in a safe place during the six to nine months it takes them to hatch. When they lay their corkscrew-shaped eggs, the cases get wedged into crevices to make sure they stay in a safe place during the six to nine months it takes them to hatch.
SPECIES IN DETAIL | Print full entry
Horn Shark
Heterodontus francisci
CONSERVATION STATUS: Data deficient
CLIMATE CHANGE:
Blue Cavern, Casino Point
Southern California and the Channel Islands to the Gulf of California and Baja California
Horn sharks rarely swim more than two meters (about six feet) above the substrate, tending to stick to depths between two and 11 meters (between six and 36 feet). When they’re younger, they usually stick to depths shallower than 10 meters (about 33 feet). They go a little bit deeper as they get older (but not much). Occasionally, these sharks have been spotted as deep as 150 meters (492 feet).
These sharks have a very distinctive appearance. They have high ridges above their eyes, topping off a blunt, short head. They range from various shades of gray or muddy brown with dark brown or black spots, with spines on their dorsal fins and anal fin. (These spines are where their “horn” moniker comes from.) Their dorsal fins are very broad and muscular, spanning a larger portion of their body than other sharks — they can use these fins to help them crawl along the ocean bottom.
Up to a little over a meter long (about 4 feet).
These sharks are pretty inactive during the daytime, emerging at night in search of food. While they shelter in shallow rocky crevices while resting, they venture out over sandy flats, eelgrass beds, and muddy terrain to seek their meals at night, which consist largely of crustaceans, cephalopods, small fishes, lobsters, and sea urchins.
When they capture their prey, they have help from their “different teeth.” Heterodontus, their scientific name, means exactly that. It’s important because their front teeth are sharp to grasp their slippery food (cephalopods and fishes), while their back teeth are more like molars — flat — to help them crush the crustaceans and sea urchins that make up so much of their diet.
Horn shark eggs are quite unique, forming a corkscrew shape rather than the more traditional “mermaid’s purse” flat rectangular shape of other shark eggs. This corkscrew shape is very important, as it is meant to be wedged into the crevices where horn sharks spend most of their time. During the six to nine months it takes the eggs to hatch, they are more likely to remain in the place where they will have shelter and food upon hatching, rather than floating away to an unsuitable habitat.
The shape of the horn shark egg doesn’t make it completely different from other shark eggs, though. The hatching sharks still exit the egg through the side with the wider seam. The opposite end is also still narrower where it would have emerged first from the parent. Like other shark eggs, horn shark eggs also have lateral keels (a flexible structure to help anchor the egg to the ocean floor) and tendrils (a long sticky substance that also helps the egg anchor to the substrate).
These sharks are not the traveling type. Prone to what’s called high site fidelity, or sticking to one area consistently, horn sharks generally return to the same home and feeding grounds time and again. They seem to have somewhat distinct populations between islands and mainland habitats, suggesting that they prefer not to cross open water to travel.
Instead, horn sharks tend to stick to the shallow waters more readily available to them. This is fairly unique in sharks, who tend to disperse more widely, at least for reproductive purposes. Because of their tendency to stick very close to home, it may be even more important to gather more data about horn shark population levels to ensure that they remain protected in a changing ocean climate.
Before these sharks mature, they seem to spend most of their time in very shallow, warmer waters — less than about 10 meters (30 feet) of depth. As they mature and grow larger, they shift to cooler, deeper waters (more than 10 meters depth), taking refuge in bigger caves and rock ledges instead of the small crevices and overhangs of their youth.
Horn sharks are nocturnal, meaning that they are mostly active at night, preferring to hide and rest during the day. And even though they are well adapted with camouflage from their typically brown color patterns and darker spots, at least one horn shark with leucism — a lack of pigmentation resulting in a lot of white skin — has been documented as surviving quite well in La Jolla for several years. This suggests that their hiding skills and high site fidelity may help them survive as effectively as camouflage.
Horn sharks are thought to live up until around 25 years old.
The IUCN has listed their conservation status as Data Deficient. Data may be hard to come by because these sharks are with high site fidelity — they largely stick to the same places over time — and because their range is relatively small, just up the coast from the Gulf of Mexico in Mexico through southern California and the Channel Islands.
However, along this range, at least one study has identified horn sharks as being potentially vulnerable to overexploitation, particularly due to the impacts of becoming bycatch and the practices of artisanal fisheries. The study notes that the low economic value of certain species — due in part to horn sharks not being directly targeted for fishing — means that data about these species and subsequent protective measures are less readily available.
Studies have also shown that horn sharks have metabolisms that are relatively sensitive to temperature change. This may be especially true for juveniles, who seem to require a very specific, stable temperature. This temperature sensitivity implies that warming oceans may negatively impact horn sharks.
These sharks can crawl along the bottom of the ocean floor with their broad, muscular pectoral fins. The corkscrew shape of horn shark eggs allows them to get wedged into crevices, keeping them in a safe place during the six to nine months it takes them to hatch. When they lay their corkscrew-shaped eggs, the cases get wedged into crevices to make sure they stay in a safe place during the six to nine months it takes them to hatch.