Chordata · chordates

Scalloped hammerhead

Sphyrna lewini

Sphyrnidae · hammerhead sharksIUCN: Critically Endangered
Scalloped hammerhead
Photo: Kris-Mikael Krister · CC BY 2.0 · Wikimedia Commons · resized

A schooling hammerhead that gathers in huge groups at seamounts.

Fun factIts wide head spreads out electroreceptors to scan the seafloor.

Waters
Worldwide, Northeast US
Depth zone
Coastal shallows & estuaries, Open-ocean surface waters
Diet
Fish & squid
Size
Up to 4 m

Classification

Chordata › Chondrichthyes › Carcharhiniformes › Sphyrnidae

  1. Kingdom Animalia animals
    • Many-celled organisms that eat other living things for energy (heterotrophs)
    • Cells have no cell walls
    • Most can move at some stage of life
  2. Clade Bilateria bilateral animals
    • Body has a left and right side that mirror each other (bilateral symmetry)
    • Head end with concentrated nerves; three tissue layers
    • Includes about 99% of all living animal species
  3. Clade Deuterostomia deuterostomes
    • In the embryo, the first opening becomes the anus and the mouth forms second
    • Includes echinoderms and chordates
  4. Phylum Chordata chordates
    • At some stage of life: a stiffening rod along the back (notochord)
    • A hollow nerve cord along the back (dorsal)
    • Slits in the throat (pharyngeal slits) and a tail past the anus
  5. Subphylum Vertebrata vertebrates
    • A skull (cranium) protecting a brain
    • Backbone or similar support around the nerve cord
    • Includes fishes, amphibians, reptiles, birds, and mammals
  6. Infraphylum Gnathostomata jawed vertebrates
    • Jawed vertebrates: jaws formed from gill arches
    • Paired fins or limbs
    • Includes all fishes except hagfish and lampreys, plus all tetrapods
  7. Class Chondrichthyes cartilaginous fishes
    • Skeleton made of cartilage, not bone
    • Skin covered in tooth-like scales (denticles)
    • Teeth constantly replaced; males have claspers for mating
  8. Subclass Elasmobranchii sharks & rays
    • Sharks and rays: five to seven separate gill slits on each side
    • Many rows of replaceable teeth
  9. Clade Selachii sharks
    • Sharks: gill slits on the sides of the head
    • Pectoral fins not joined to the head
  10. Superorder Galeomorphii galeomorph sharks
    • Sharks with an anal fin and five gill slits
    • Includes most familiar sharks
  11. Order Carcharhiniformes ground sharks
    • Ground sharks: lower eyelid (nictitating membrane) that closes over the eye
    • Anal fin and two dorsal fins
    • The largest shark order
  12. Family Sphyrnidae hammerhead sharks
    • Hammerheads: head flattened into a wide 'hammer' (cephalofoil)
  13. Genus Sphyrna
    • Species in the same genus are very close relatives and often look alike.
  14. Species Sphyrna lewini Scalloped hammerhead

Closest relatives in the guide