# Hammerhead Shark — Facts, Threats & Conservation

*Sphyrnidae*

> Hammerhead sharks are a family of coastal and open-ocean sharks (Sphyrnidae) instantly recognised by the flattened, hammer-shaped head, or cephalofoil, that spreads their eyes and sensory organs wide apart. Species range from under a metre to more than 6 m long, with large individuals weighing around 230 kg.

**IUCN status:** Critically Endangered  ·  **WARN range:** Oceans

## Quick facts
| Fact | Value |
| --- | --- |
| Scientific name | Sphyrnidae (family) |
| Diet | Carnivore |
| Habitat | Warm coastal and open oceans worldwide |
| Lifespan | 20–30 years or more |
| Length | 0.9 m to over 6 m by species |
| Top speed | Around 40 km/h (25 mph) in bursts |
| Conservation status | Critically Endangered (great hammerhead) |

## Scientific classification
- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Chondrichthyes
- **Order:** Carcharhiniformes
- **Family:** Sphyrnidae
- **Genus:** Sphyrna

## Conservation status
- **Status:** Critically Endangered (IUCN Red List category)
- **Population:** Global population not compiled for this guide
- **Trend:** See the IUCN Red List assessment
- **Assessed:** See the IUCN Red List assessment
- **CITES:** See CITES appendices
- Conservation figures are drawn from the IUCN Red List and CITES; this guide links to the authoritative sources rather than restating population counts.

## Key facts: Hammerhead Shark
- The wide, flattened head that gives these sharks their name is called a cephalofoil, and it is more than an odd silhouette.
- Hammerheads are carnivores that feed on bony fish, squid, octopus, crustaceans and other sharks, but they are best known for hunting stingrays.
- The family Sphyrnidae contains around nine species, and they vary enormously in size.

## The hammer-shaped head
The wide, flattened head that gives these sharks their name is called a cephalofoil, and it is more than an odd silhouette. Spacing the eyes far apart gives the shark a broader field of vision, while the underside is packed with electroreceptors called ampullae of Lorenzini that detect the faint electrical signals of buried prey. Sweeping the head from side to side lets a hammerhead scan the seabed like a metal detector. The shape also acts as a hydrofoil, helping the shark bank and turn sharply as it swims.

## Hunting and diet
Hammerheads are carnivores that feed on bony fish, squid, octopus, crustaceans and other sharks, but they are best known for hunting stingrays. A hammerhead will pin a ray to the seabed with the edge of its head, then pivot to take bites from the disc. Many individuals seem largely unbothered by the venomous barbs of their prey, and rays recovered from their stomachs are sometimes studded with spines. Larger species hunt alone, cruising close to the bottom where their electrical sense works best.

## Size and species
The family Sphyrnidae contains around nine species, and they vary enormously in size. The small bonnethead reaches under a metre, while the great hammerhead can exceed 6 m and weigh in the region of 230 kg, making it one of the largest predatory sharks. The scalloped and smooth hammerheads fall between these extremes. Despite their formidable appearance, hammerheads pose little danger to people, and unprovoked bites are very rare.

## Where they live
Hammerheads swim through warm temperate and tropical waters around the world, along coastlines, over continental shelves and out into the open ocean. They are found from shallow lagoons and coral reefs to depths of several hundred metres. Some species, notably the scalloped hammerhead, gather in large schools around seamounts and offshore islands, particularly by day. These aggregations can number in the hundreds and are a famous sight for divers.

## Reproduction
Hammerheads give birth to live young rather than laying eggs, nourishing the developing pups through a placenta-like connection inside the mother. Litters range from around a dozen to more than 40 pups depending on the species. The newborns are miniature versions of the adults, with heads that are more rounded at birth and flatten as they grow. Coastal nursery areas in shallow water shelter the young from larger predators during their vulnerable first months.

## Why the great hammerhead is Critically Endangered
The great hammerhead is listed as Critically Endangered by the IUCN, and several other hammerhead species are also threatened. Their large fins are highly valued in the shark-fin trade, and the sharks are frequently caught both deliberately and as bycatch in commercial fisheries. Hammerheads are especially vulnerable because they are slow to mature and produce relatively few young. They also suffer very high stress levels when hooked, so many die even when released.

## What WARN does
WARN does not run a dedicated hammerhead shark programme — this guide is part of the World Animal Rescue Network's free educational library. The hammerhead shark faces documented conservation pressure in the wild, which is why clear, sourced public information about it matters. Building public understanding of species like the hammerhead shark supports the broader conservation awareness that underpins WARN's partner-led rescue work across its network.

If clear, science-based wildlife guides like this help you understand and value animals, please consider supporting the World Animal Rescue Network's educational and rescue work so we can keep producing them.

## Frequently asked questions: Hammerhead Shark
### Why do hammerhead sharks have such strange heads?
The wide, flattened head, called a cephalofoil, spreads the eyes and electrical sensors far apart. This gives the shark a wider field of vision and a better ability to detect prey hidden in the sand. The shape also helps the shark turn quickly as it swims.

### Are hammerhead sharks dangerous to humans?
Hammerheads look intimidating but rarely pose a threat to people. Unprovoked bites are extremely uncommon, and most encounters involve the shark simply swimming away. Only the largest species could realistically injure a swimmer, and they show little interest in humans.

### How big do hammerhead sharks get?
Size varies greatly by species. The small bonnethead stays under a metre, while the great hammerhead can exceed 6 m and weigh around 230 kg. This makes the great hammerhead one of the largest predatory sharks in the ocean.

### What do hammerhead sharks eat?
Hammerheads are carnivores that eat fish, squid, octopus, crustaceans and other sharks. They are particularly known for hunting stingrays, which they pin to the seabed with their broad heads. They often appear immune to the rays' venomous barbs.

### How long do hammerhead sharks live?
Hammerheads are long-lived sharks, typically reaching 20 to 30 years and sometimes more. Their slow growth and late maturity are part of why overfishing has hit their populations so hard, as they cannot replace their numbers quickly.

### Why are hammerhead sharks endangered?
The great hammerhead is Critically Endangered, mainly because of the shark-fin trade and heavy accidental capture in fisheries. Hammerheads mature slowly and have small litters, so populations recover slowly. They also die easily from the stress of being hooked, even when released.

### Where do hammerhead sharks live?
Hammerhead Sharks live in Warm coastal and open oceans worldwide. Hammerhead sharks are a family of coastal and open-ocean sharks (Sphyrnidae) instantly recognised by the flattened, hammer-shaped head, or cephalofoil, that spreads their eyes and sensory organs wide apart.

## Sources
- [Wikipedia — Hammerhead Shark](https://en.wikipedia.org/wiki/Hammerhead_shark)
- [Wikidata — Hammerhead Shark](https://www.wikidata.org/wiki/Q208490)

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Full guide: https://worldanimalrescuenetwork.org/wildlife-guides/hammerhead-shark