common sea hare vs Great Hammerhead

Aplysia punctata compared with Sphyrna mokarran

Key Differences

• common sea hare is Least Concern while Great Hammerhead is Critically Endangered.

Taxonomic Classification

Rank	common sea hare	Great Hammerhead
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Mollusca (Mollusks)	Chordata (Chordates)
Class	Gastropoda (Gastropoda)	Chondrichthyes (Cartilaginous Fish)
Order	Aplysiida (Aplysiida)	Carcharhiniformes (Ground Sharks)
Family	Aplysiidae	Sphyrnidae (Hammerhead Sharks)
Genus	Aplysia	Sphyrna (Hammerhead Sharks)
Species	Aplysia punctata	Sphyrna mokarran

Evolutionary Relationship

common sea hare and Great Hammerhead share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

common sea hare

LC — Least Concern

Great Hammerhead

CR — Critically Endangered

Trend: Decreasing ↓

Physical Characteristics

Attribute	common sea hare	Great Hammerhead
Diet	—	Carnivore
Average Lifespan	—	40 years
Average Length	—	5.0 m
Average Weight	—	450.0 kg

Habitat & Geographic Range

common sea hare

Habitat

Typically found in terrestrial and aquatic habitats including forests and freshwater.

Range

Distributed across Denmark, Norway, Portugal, and Sweden.

Great Hammerhead

Habitat

Found across multiple habitat types including tropical and subtropical moist broadleaf forests, tropical and subtropical dry broadleaf forests, and flooded grasslands and savannas, among 5 distinct biome types spanning the Indomalayan and Neotropic and Oceanian realms. Populations are also found in montane and highland environments at higher elevations.

Range

Distributed across Colombia, Taiwan, and Venezuela. Currently classified as Critically Endangered on the IUCN Red List, this species faces significant conservation challenges across its range.

common sea hare

<em>Aplysia punctata</em>, the common sea hare, is a large opisthobranch sea slug in the family Aplysiidae, order Aplysiida, found in the northeastern Atlantic Ocean and Mediterranean Sea, with confirmed records from Denmark, Norway, Portugal, and Sweden. This species typically inhabits shallow subtidal and intertidal zones with abundant macroalgae, feeding primarily on red and green algae — a diet that influences the color of the defensive purple ink it secretes when threatened. <em>Aplysia punctata</em> is a simultaneous hermaphrodite, capable of acting as both male and female during mating, and often forms mating chains involving multiple individuals. It can reach considerable size among European opisthobranch species, though body dimensions vary considerably with age and feeding conditions. The species is classified as Least Concern by the IUCN, reflecting stable populations across its coastal range. Biological traits for this species remain poorly documented in the scientific literature, including precise average data on lifespan, body length, weight, and detailed seasonal dietary patterns, though its general herbivorous feeding on macroalgae is well established.

Great Hammerhead

The largest hammerhead shark species, great hammerheads reach up to 6 meters and are found in tropical and subtropical coastal waters worldwide. Their distinctive T-shaped head (cephalofoil) dramatically increases sensory surface area for electroreception, enabling them to detect buried stingrays through sand with exceptional precision — stingrays are a preferred prey. Critically Endangered, with populations declining dramatically due to highly valued fins and bycatch mortality.