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Horn and Angel Sharks: Predators on the Seabed

Updated on September 6, 2017
AliciaC profile image

Linda Crampton is a science teacher with an honors degree in biology. She loves to study nature and write about animals and plants.

A crested horn shark (or crested bullhead shark) feeds on the egg of another species of bullhead shark.
A crested horn shark (or crested bullhead shark) feeds on the egg of another species of bullhead shark. | Source

Unusual Fish

Many people think of sharks as ferocious killing machines that swim at high speed as they hunt for prey. This image is often inaccurate, however. First, research is showing that far from being "machines", at least some sharks are surprisingly intelligent. Secondly, not all sharks move fast or swim through the open ocean. Some, including the horn shark and the angel shark, live and feed on the seabed. Neither fish is a typical shark.

Horn sharks have a raised ridge above each eye. The ridges look like little horns and may have given the animals their name. The fish also have a blunt snout that resembles the snout of a bull. Horn sharks often hunt for food by "walking" over objects with their strong pectoral fins. They swim quite slowly compared to most other sharks.

Angel sharks have a wide, flattened body and wing-like pectoral fins. They hide in the sediments on the seabed with just their eyes above the ground, bursting out of their hiding place in order to capture passing prey.

External Anatomy and Fins of a Typical Shark

Source
Divers can often get close to California horn sharks. This is usually - but not always - safe.
Divers can often get close to California horn sharks. This is usually - but not always - safe. | Source

Heterodontus, the genus name of bullhead sharks, is derived from two Greek words: heteros, which means "different", and odont, which means "teeth". The name refers to the two types of teeth in the shark's mouth.

Features of Bullhead Sharks

Horn sharks are members of an order of fish known as bullhead sharks (Heterodontiformes). There are nine known species in this order, all belonging to the genus Heterodontus. The term "horn shark" is applied to three of the species—the California horn shark, the Mexican horn shark, and the crested horn shark.

The snout of a bullhead shark is blunt.There is a round opening on each side of the snout known as an oronasal groove. Each of these openings is surrounded by a fleshy ring of tissue.

The shark's teeth are adapted for grasping and grinding hard foods gathered from the seabed, such as sea urchins and crabs. The front teeth are pointed to enable efficient biting and the back teeth are flattened for crushing,

Bullhead sharks have a crest over each eye and a spine in front of each of their two dorsal fins (the fins on the shark's back). Some reports say that the fin spines gave the horn sharks their name rather than the crest over their eyes. The pectoral fin on each side of the body is large and muscular and enables the fish to move with a walking motion over the ocean bottom.

Bullhead sharks generally aren't dangerous to humans, although they may bite or chase when threatened. They shouldn't be confused with bull sharks, which are aggressive.

A California horn shark
A California horn shark | Source

The California Horn Shark

The California horn shark (Heterodontus francisci) lives on the west coast of North America from the state of California to the Gulf of California. It's an attractive fish with a brown or grey surface that has darker spots. It reaches a maximum length of four feet. Most individuals are shorter than this, however.

The fish is usually a nocturnal animal. During the day it hides in caves or crevices, under ledges, or in thick beds of seaweed. Starting at dusk, it hunts for animals on or close to the seabed, including crabs, snails, squid, shrimp, sea urchins, sea stars (starfish), and occasionally fish. It's able to remove animals attached to a substrate by using its teeth like a chisel. Suction helps draw the prey into the shark's mouth. The shark may also pry animals off a surface with its mouth by bracing itself with its pectoral fins, moving into a vertical position and then rapidly moving its body downwards, in effect using its body as a lever.

A Horn Shark off Catalina Island

Reproduction

Fertilization is internal in all sharks. Fish have a pelvic fin on each side of their body behind the pectoral fins. A male shark has a tubular organ called a clasper on the inner side of each of his pelvic fins. Claspers insert sperm into the female's reproductive tract.

After fertilization, the female horn shark reproduces by laying eggs. She produces two eggs at a time, starting in the late winter or early spring. There is a gap of eleven to fourteen days between egg laying sessions. Eggs are produced for as long as four months.

The egg case has a spiral shape. It's soft when it's laid and gradually hardens over time. The female wedges each egg into a rock crevice to protect it from predators. The embryo takes a long time to develop. Pups aren't born until six to eight months after the eggs are laid. The typical lifespan of California horn sharks isn't known for certain, but they have lived for twelve years in captivity. Some reports say that they can live for as long as twenty-five years.

An Angel Shark Blending in with its Background

Source

Angel Sharks

Angel sharks belong to the order Squatiniformes and the genus Squatina. There are twenty-three known species. The front section of an angel shark's body is flattened. The fish has greatly enlarged pectoral fins that are flat and extend outwards. They often look like wings. The smaller pelvic fins also extend out from the body.

The rear section of an angel shark's body isn't flattened and looks more like that of a typical shark. However, the lower lobe of the tail is longer than the upper lobe. In other sharks, the upper lobe is longer than the lower lobe.

Like horn sharks, angel sharks are bottom feeders. Instead of actively patrolling the ocean bottom, however, they use an ambush technique to catch their prey. They cover themselves with a thin layer of sediment on the seabed so that just their eyes show and then patiently wait. When they detect a suitable prey animal they pounce. The sharks have powerful jaws and sharp teeth, which make them very successful predators.

Angel sharks are generally not dangerous to humans. If a person gets too close to the jaws, though, they may get a nasty wound. It should never be assumed that a totally still angel shark is dead because it almost certainly isn't.

Swimming in the Wild

Unlike some sharks that must swim continually to force water over their gills, angel sharks (and horn sharks) have muscles that pump water over their gills. Therefore they can remain motionless and still survive.

Feeding in Captivity

The Pacific Angel Shark

The Pacific angel shark (Squatina californica) lives in the eastern part of the Pacific Ocean. Its range extends from Alaska down into South America. The fish reaches a maximum length of about five feet but is usually shorter than this.

The shark is brown or grey with dark spots. The mottled surface appearance is very useful for camouflaging the fish against the ocean bottom. The pectoral and pelvic fins are noticeably angular and pointed. The shark also has barbels around its mouth. Barbels are slender sensory organs that are sensitive to both taste and touch.

A Pacific angel shark
A Pacific angel shark | Source

Catching Prey

Like the California horn shark, the Pacific angel shark is more active during the night than the day. It feeds mainly on fish and squid. Research suggests that sight is the most important factor in the shark's detection of food. Scientists say that when the sharks hunt at night, bioluminescence created by planktonic organisms may help them to see their prey. Another very interesting discovery has been made by high speed videography. The researchers who conducted this experiment found that the sharks caught their prey in about one tenth of a second.

A Close-Up View of a Camouflaged Fish

Egg Production

Angel sharks give birth to live young. Eggs are produced, but they hatch inside their mother's body. The pups feed on yolk stored in a yolk sac until they are born. The Pacific angel shark produces about six pups at a time. The gestation period may vary, but it seems to be about ten months. There are reports that the shark can live for as long as thirty-five years. This needs to be confirmed, however.

A Camouflaged Fish Is Disturbed

Population Status of the Two Fish

The IUCN (International Union for Conservation of Nature) classifies animal species according to their nearness to extinction. The California horn shark has been placed in the Data Deficient category. This means that the size of its population isn't known.

The shark generally isn't caught for food, but it is sometimes caught for its long fin spines, which are used in jewelry. Today the main problem for the horn shark seems to be that it forms part of the bycatch. "Bycatch" is defined as a fish or animal that is caught accidentally when another type of fish is being caught. Luckily, the horn shark seems to be a hardy animal. When it's returned to the ocean after being accidentally caught it often survives.

The Pacific angel shark is classified in the Near Threatened category. There was a period in the 1970s and 1980s when it was caught for food in the United States, which had a very serious effect on the shark's population. New fishing regulations mean that the species is recovering in the US, but the effect of the Mexican shark fishery on the species is unknown.

The Crested Horn Shark in Australia

The big sharks that are dangerous to humans are generally better known by the public than the smaller, bottom-dwelling fish. This is a shame, because the sharks that roam the seabed or hide in its sediments are interesting animals. They are definitely worthy of our attention.

References

  • "Horn Shark." Monterey Bay Aquarium. https://www.montereybayaquarium.org/animal-guide/fishes/horn-shark (accessed August 31, 2017).
  • "Heterodontus francisci." International Union for Conservation of Nature. http://www.iucnredlist.org/details/39333/0 (accessed August 31, 2017).
  • "Squatina californica." University of Florida. https://www.floridamuseum.ufl.edu/fish/discover/species-profiles/squatina-californica/(accessed August 31, 2017).
  • "Squatina californica." International Union for Conservation of Nature. http://www.iucnredlist.org/details/39328/0 (accessed August 31, 2017).

© 2014 Linda Crampton

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    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thank you, Anita! I appreciate your comment and the vote.

    • Anita lesic profile image

      Dream Lover 3 years ago from Zagreb

      Voted up. Very interesting hub and beautiful pictures :)

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thank you very much, VioletteRose! I appreciate your visit.

    • VioletteRose profile image

      VioletteRose 3 years ago from Chicago

      Great details about the horn shark and angel shark. As you mentioned, the picture of a shark in my mind was something that swims and hunts. Thanks for sharing !

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Hi, ologsinquito. Yes, I think the horn shark is an attractive and interesting fish. Thanks for the visit.

    • ologsinquito profile image

      ologsinquito 3 years ago from USA

      The California horn shark is very attractive. I don't remember seeing one, even though I've been to the Monterey aquarium numerous times.

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thanks for the comment, Deb! It's certainly a very sad thought that some fish are being killed so that their spines can be used to make jewelry.

    • aviannovice profile image

      Deb Hirt 3 years ago from Stillwater, OK

      Amazingly wonderful information on these animals. As far as jewelry goes, I think what these creators need is a little plastic, don't you?

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Hi, Dianna. I live close to the ocean, too, but luckily no dangerous sharks live nearby. The number and variety of animals on Earth is certainly amazing!

    • teaches12345 profile image

      Dianna Mendez 3 years ago

      Living so close to the ocean, we know the dangers of shark swimming close to the beach. It is not a daily threat, but one has to be aware of the potential. I learned lots about different types of sharks from your post. always come away amazed at the variety of animals.

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thank you very much for the comment and the vote, Eddy.

    • Eiddwen profile image

      Eiddwen 3 years ago from Wales

      You sure have outdone yourself here Alicia.

      Voted up.

      Eddy.

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thank you very much for the lovely comment and all the votes. D.A.L.! I love learning about nature, too. It's a fascinating and very enjoyable activity.

    • D.A.L. profile image

      Dave 3 years ago from Lancashire north west England

      Fantastic hub , thoroughly enjoyed reading and the pictures are amazing. As a naturalists I never tire of being taught about animals of the world. Here I have been educated well by this inspiring work. Thank you. Voted up,interesting and beautiful.

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thanks for the visit, Vellur! I appreciate your comment and vote.

    • Vellur profile image

      Nithya Venkat 3 years ago from Dubai

      Interesting and informative hub about sharks, learned a lot about sharks after reading your hub. Thank you for sharing and voted up.

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Hi, Nell. Yes, sharks are definitely amazing creatures! Thank you very much for the comment, the vote and the share. I appreciate them all!

    • Nell Rose profile image

      Nell Rose 3 years ago from England

      Hi Alicia, fascinating hub about the Sharks, they are the most amazing creatures, and I didn't realise that some sharks could stay stationary, I learned something new, great hub! voted up and shared, nell

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Hi, b. Malin. Thanks for the comment and the votes. It will be very interesting to confirm that the angel shark can live that long! It's a fascinating animal. Luckily, the angel and the horn shark generally aren't aggressive towards humans.

    • b. Malin profile image

      b. Malin 3 years ago

      A Great SAFE way to learn about ALL these Sharks... They really are a Fascinating read, thanks to your enlightening Hub. Alicia. I didn't know anything about their reproduction, or how long they can live...Thirty-five years for some...Wow...what are the chances of an attack by one?

      Voted UP & Interesting.

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thank you so much for the comment and for showing the hub to your girls, Robin! I'm very interested in sharks, too. They are important animals, as you say. I think that both the angel and the horn shark look cool!

    • Robin profile image

      Robin Edmondson 3 years ago from San Francisco

      I am a huge shark lover, and I always appreciate Hubs that educate people on their importance. Our oceans are such a fragile ecosystem and our destruction of the top of the food chain has a huge impact on us all.

      I had never heard of the California Horned Shark before your Hub. What a cool looking animal. Will definitely be showing this Hub to my girls!

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thank you, DDE. These sharks are interesting!

    • DDE profile image

      Devika Primić 3 years ago from Dubrovnik, Croatia

      Horn and Angel Sharks - Predators on the Seabed are unique creatures and is most interestingly explained in this hub.

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thank you very much for the comment, the votes and the share, Faith! It's fascinating to study life in the oceans. There is so much to discover! Blessings to you, Faith.

    • AliciaC profile image
      Author

      Linda Crampton 3 years ago from British Columbia, Canada

      Hi, Bill. I agree - the last video is amazing! It's sad too, although it wasn't sad for the angel shark. When I first watched the video I was so glad that the horn shark escaped, and then almost immediately the angel shark ate a different fish! Thank you very much for the vote and the share. I hope that your week is great, too.

    • Faith Reaper profile image

      Faith Reaper 3 years ago from southern USA

      Fascinating creatures, the Horn and Angel Sharks! Your hubs are always so very interesting. I, too, just love reading and learning about sea life. Great article.

      Up and more and sharing

      Blessings,

      Faith Reaper

    • bdegiulio profile image

      Bill De Giulio 3 years ago from Massachusetts

      Amazing creatures Linda. Thanks you for bringing them to us. That video of the Angel Shark trying to eat the Horn Shark is amazing. Have a great week. Voted up and shared.

    • AliciaC profile image
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      Linda Crampton 3 years ago from British Columbia, Canada

      Thanks, EGamboa. Life is very different under the ocean than on land!

    • AliciaC profile image
      Author

      Linda Crampton 3 years ago from British Columbia, Canada

      Hi, Bill. Thanks for the comment and for sharing your experience with bullhead fish.

    • EGamboa profile image

      Eileen Gamboa 3 years ago from West Palm Beach

      Point of view from the ocean. Very interesting.

    • billybuc profile image

      Bill Holland 3 years ago from Olympia, WA

      I've caught a few bullheads in my time. Not a pleasant experience. LOL I love hubs about the animal kingdom....and fish...and birds....and...and....

      Thanks for an enjoyable read, Alicia.

    • AliciaC profile image
      Author

      Linda Crampton 3 years ago from British Columbia, Canada

      Thanks for the comment and the vote, Jodah. I think that sea life is very interesting, too. There is so much to discover under the ocean surface!

    • Jodah profile image

      John Hansen 3 years ago from Queensland Australia

      Very interesting. I find all sea creatures, especially the lesser known varieties intriguing. Good hub. Vote up.