American Oceans

Bonnethead Shark

The Bonnethead shark is a unique species of shark that is part of the hammerhead family. It is known for its distinctive shovel-shaped head, which sets it apart from other shark species.

a bonnethead shark on the shore of a beach

Bonnethead sharks are found in warm coastal waters, and they are known for their highly migratory behavior.

Despite their fearsome appearance, Bonnethead sharks are relatively small and harmless to humans.

They are typically found in small groups of five to fifteen individuals, although schools of hundreds or even thousands have been reported. Bonnethead sharks are active swimmers, constantly moving to follow changes in water temperature and to maintain respiration.


Habitat and Distribution

The Bonnethead shark (Sphyrna tiburo) is a small species of hammerhead shark found in the shallow waters of the western Atlantic, from New England to Brazil, and the eastern Pacific, from southern California to Ecuador.

a bonnethead shark swimming

They prefer warmer waters over 70°F (21°C) and can be found in a variety of environments, including estuaries, bays, seagrass beds, mud, and sandy bottoms, as well as coral reefs along the coastline.

Bonnetheads are highly adaptable and can thrive in a wide range of habitats. They are often found in salt marshes and lagoons, where they can feed on small fish, crabs, and shrimp.

These sharks also inhabit intertidal zones, where tidal fluctuations create diverse habitats.

In terms of distribution, Bonnetheads can be found in the Caribbean Sea and the Gulf of Mexico, where they are commonly found in shallow coastal waters.

They are also found along the Pacific coast of North and South America, from southern California to Ecuador.

Bonnetheads are typically found in small schools of up to 15 individuals, although during migration events, they can be seen in groups of hundreds or thousands.

They are a highly migratory species and can move long distances in search of food and suitable habitats.


Physical Characteristics

Bonnethead sharks are a unique species of shark with a distinctive head shape that resembles a shovel.

a close up of a bonnethead shark

They are the smallest of the ten hammerhead shark species, with a smooth and rounded head between the eyes.

Bonnethead sharks are highly migratory and can be found in coastal inshore waters.

Size and Weight

Bonnethead sharks are relatively small, with females reaching sexual maturity at around 32 inches and males at around 24 inches.

They have one of the shortest gestation periods among sharks, lasting only 4.5-5.0 months, and give birth to four to twelve pups in late summer and early fall, measuring 12 to 13 inches in length.

Bonnetheads can grow up to a maximum length of about 5 feet and typically weigh around 20-25 pounds.

Color and Morphology

Bonnethead sharks have a gray or grayish-brown back that often has small dark spots, with a white underside.

They have sharp teeth that are used to catch and eat crustaceans, mollusks, and small fish.

Bonnethead sharks exhibit sexual dimorphism, with the male possessing a distinct bulge on the top of its head, a unique feature of the hammerhead species.

The morphology of Bonnethead sharks is unique among the hammerhead species. Unlike most species that have straight heads with notched edges, those of Bonnetheads are smooth and rounded between the eyes.

The head is broadly widened into the shape of a shovel, which is where the name “shovelhead” comes from.

Bonnetheads do not have an interdorsal ridge, which is a distinguishing characteristic from other hammerhead sharks.


Reproduction

Bonnethead sharks are viviparous, meaning they give birth to live young instead of laying eggs.

a bonnethead shark swimming

Each litter produces around 8-12 pups, and the gestation period is approximately 4-5 months. Not much is known about their mating behavior, but they reproduce by mating sexually.

Diet

Bonnethead sharks are omnivorous, feeding on a variety of prey including small fish, squid, crustaceans, and seagrasses.

They are opportunistic feeders and have been known to eat whatever prey is available.

Their diet primarily consists of crustaceans, such as blue crabs and shrimps, but they also eat mollusks and small fish.

Feeding Behavior

The bonnethead shark’s feeding behavior involves swimming across the seafloor, moving its head in arc patterns like a metal detector, looking for minute electromagnetic disturbances produced by crabs and other creatures hiding in the sediment.

They are relatively slow swimmers and prefer to ambush their prey from below. Bonnethead sharks are not aggressive towards humans and prefer to avoid contact if possible.

Bonnethead sharks are common, coastal inshore sharks, found in shallow bays and seagrass beds.

They are the smallest of the ten hammerhead shark species, and their head shape is unique among the species.

Unlike most species that have straight heads with notched edges, those of bonnetheads are smooth and rounded between the eyes.

Bonnethead sharks are often caught by fisheries for their fins, but they are not considered a threatened species.

They are a popular game fish and can be caught on light tackle. To grind up their food, bonnethead sharks have teeth that are adapted for crushing hard shells, such as those found on crabs and shrimps.

Their feeding behavior involves swimming across the seafloor, moving their head in arc patterns to detect electromagnetic disturbances produced by their prey. Bonnethead sharks are not aggressive towards humans and prefer to avoid contact if possible.


Human Interaction

Bonnethead sharks are not typically targeted by humans for commercial or recreational purposes, but they are often caught as bycatch in shrimp trawls, longlines, and hook-and-line fishing.

Bonnethead Shark swimming in ocean in natural habitat

The meat of bonnethead sharks is marketed for human consumption, and it is also processed into fishmeal. However, despite being edible, this species is of little economic importance.

Human Consumption

Bonnethead sharks are considered to be safe for human consumption and are utilized fresh, frozen, or dry-salted. Their meat is marketed for human consumption, but it is not a significant source of food for humans.

Aquariums and Aquaria

Bonnethead sharks are commonly found in aquariums and aquaria around the world. They are popular exhibits due to their unique head shape and relatively small size.

However, they require a large tank with plenty of swimming room and a varied diet to thrive in captivity.

Predators and Crush

Bonnethead sharks have few natural predators in the wild, but they are sometimes preyed upon by larger sharks, including hammerheads.

They are generally harmless to humans and are not known to attack or bite people.

Cerebrospinal Fluid and Communication

Bonnethead sharks have a unique way of communicating with other members of their species.

They release a cerebrospinal fluid to inform others of their location. This fluid is released through the skin and is thought to be a form of chemical communication.

Vision

Bonnethead sharks have excellent vision and are able to see in both bright and dim light. They have a unique head shape that allows them to see in a wider range of angles than other sharks.

This wider head also provides space for more ampullae of Lorenzini to help detect prey, and also possibly function as a navigation aid.


Scientific Classification

The Bonnethead Shark, also known as Sphyrna tiburo, is a member of the hammerhead shark family, Sphyrnidae.

a bonnethead shark on a white background

It is the smallest species of hammerhead shark, with an average length of 2.6-3.0 ft and a maximum length of 4.9 ft.

The Bonnethead Shark belongs to the Kingdom Animalia, Phylum Chordata, and Class Chondrichthyes.

Chondrichthyes is a class of cartilaginous fish that includes sharks, rays, and chimaeras. They have a skeleton made of cartilage rather than bone.

The Bonnethead Shark belongs to the order Carcharhiniformes, which includes over 270 species of shark. They are characterized by their five to seven gill slits, a heterocercal caudal fin, and a streamlined body.

The Bonnethead Shark belongs to the family Sphyrnidae, which includes nine other species of hammerhead sharks.

Hammerhead sharks are known for their unique head shape, which is flattened and extended into a “hammer” shape. The Bonnethead Shark is the only hammerhead species that has a head that is more rounded than hammer-shaped.

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