Common hammerhead vs Common Seal

Sphyrna zygaena compared with Phoca vitulina

Key Differences

• Common hammerhead is Not Evaluated while Common Seal is Near Threatened.

Taxonomic Classification

Rank	Common hammerhead	Common Seal
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class	Chondrichthyes (Cartilaginous Fish)	Mammalia (Mammals)
Order	Carcharhiniformes (Ground Sharks)	Pinnipedia (Seals & Sea Lions)
Family	Sphyrnidae (Hammerhead Sharks)	Phocidae (True Seals)
Genus	Sphyrna (Hammerhead Sharks)	Phoca (Harbor Seals)
Species	Sphyrna zygaena	Phoca vitulina

Evolutionary Relationship

Common hammerhead and Common Seal share a common ancestor at the Phylum level: Chordata. (Chordates)

Conservation Status

Common hammerhead

NE — Not Evaluated

Common Seal

NT — Near Threatened

Population: ~500.0K

Trend: Stable →

Physical Characteristics

Attribute	Common hammerhead	Common Seal
Diet	—	Carnivore
Average Lifespan	—	30 years
Average Length	—	1.7 m
Average Weight	—	80.0 kg

Habitat & Geographic Range

Common hammerhead

Habitat

Typically found in marine environments from coastal waters to deep ocean.

Range

Distributed across Chile, Denmark, Portugal, Sweden, and Taiwan.

Common Seal

Habitat

Typically found in diverse ecosystems where prey species are available.

Range

Found across Europe (7 countries) and North America (United States). Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

Common hammerhead

The common hammerhead, <em>Sphyrna zygaena</em>, is a cartilaginous fish belonging to the order Carcharhiniformes, family Sphyrnidae. This species is typically found in marine environments and has a distribution that includes the waters of Chile, Denmark, Portugal, Sweden, and Taiwan, reflecting a wide range across both Atlantic and Pacific Ocean systems. As a hammerhead shark, <em>Sphyrna zygaena</em> possesses the characteristic cephalofoil, the laterally expanded head structure that provides enhanced sensory capabilities and hydrodynamic benefits. Hammerhead sharks are generally known to be active, wide-ranging predators within marine ecosystems. No dietary information has been provided for this specific species in current records. Biological traits of this species remain poorly documented in the scientific literature.

Common Seal

The most widely distributed pinniped, harbor seals inhabit temperate and subarctic coastal waters of both the North Atlantic and North Pacific. Adults reach up to 130 kg and spend roughly equal time at sea hunting fish, squid, and crustaceans and hauling out on beaches or rocks to rest. Their large, expressive eyes are adapted for underwater vision in low light. Harbor seals are a critical food source for orcas, sharks, and polar bears.

Shared Countries

Both species can be found in 3 countries:

🇩🇰 Denmark 🇵🇹 Portugal 🇸🇪 Sweden