Tiger shark (Galeocerdo cuvier)

IUCN Red List Status: Near Threatened

Can reach sizes larger than 18 feet

Globally distributed in tropical and warm-temperate coastal areas

Relatively fast growing and fecund species

Considered to have the most diverse diet of any shark species, with prey items including bony fish, elasmobranchs, turtles, sea birds, seals, dolphins, invertebrates, carrion, along with garbage items like plastics and license plates!

Only species in family Carcharhinidae that is ovoviviparous, meaning that the embryos develop inside eggs that are retained within the mother until hatching occurs, after which the pups leave the uterus and are born live

Litter sizes can be large, with averages around 30-35, but reported up to ~80 individuals!

Though tiger sharks are targeted as well as captured as bycatch, and there is evidence of population declines, the widespread distribution of this species, along with its relatively high growth and reproduction rates, give this species an advantage over other species when being exploited

Scalloped hammerhead (Sphyrna lewini)

IUCN Red List Status: Endangered

Distinguished by a flattened, laterally expanded head that gives this species is name

One of 10 species of hammerhead sharks!

Elaborate patterns of special sensory organs, Ampullae of Lorenzini, found along the underside of their head allows these sharks to find prey items buried within the sand

Coastal and semioceaniccircumglobal distribution in warm temperate and tropical waters

Particularly vulnerable because all life stages are subject to directed and non-directed fishing capture

Because of high fin ray (the supportive structures in shark fins) numbers, hammerhead fins are highly valued, which has led to increased targeting of this species

It’s been shown, worldwide, that populations segregate by sex, and when mature, females migrate to the coast to have pups

Nursery areas found in shallow inshore areas, while adults are more offshore

Maximum sizes reported up to ~11 feet

This species known for their schooling behavior, where number of individuals can be several hundred at a time

Oceanic whitetip shark (Carcharhinus longimanus)

IUCN status: vulnerable

Max length at 13 feet

Easily recognized by their characteristic large first dorsal fin, and long, white-tipped, pectoral fins

Oceanic, deep-water sharks, distributed world-wide in tropical and sub-tropical locations

These sharks are viviparous, meaning the pups have a placental connection while in the uterus

Gestation takes 10-12 months

Very active, highly-migratory, and curious sharks

The large, highly-prized, fins on this shark make it particularly vulnerable to the shark-fin trade

Reproductive maturity at 4-5 years, which is relatively early for sharks!

This species has been known to trail pilot whales, looking for food

Shortfin mako shark (Isurus oxyrinchus)

IUCN Red List status: Vulnerable

The shortfin mako is one of two species in the genus Isurus, the other being the longfin mako (Isurus paucus)

The shortfin mako is in the same family (Lamnidae) as the great white shark

Global and pelagic distribution

Maximum length ~13 feet

In utero embryos gain nourishment from a yolk sack, as well as feeding on other eggs/smaller embryos in the uterus (called “uterine cannibalism”), in a form of reproduction called ovoviviparity

Shortfin mako sharks reproduce every 3 years

Shortfin mako sharks are probably the fastest of all sharks, often obtaining speeds of 22 mph, and can leap from the water

The mako has a body designed to reduce drag and increase thrust, resulting in greater swimming speeds that allow the shark to exploit fast prey species such as swordfish and tuna; their needle-like teeth allow for puncturing and snagging these prey items

Like the white shark, the shortfin mako has muscle and vascular structures that allow the shark to be regionally endothermic; with warmer swimming muscles, the overall performance of the shark is enhanced!

It takes 15-18 months for babies to develop in their mothers!

Blacktip shark (Carcharhinus limbatus)

IUCN Red List Status: Near Threatened

Found in warm-temperate, subtropical, and tropical waters worldwide

This species is seen in waters off of beaches, and in bays, estuaries, coral reefs, and river mouths

Blacktips eat primarily bony fishes, and also crustaceans such as shrimp and crabs

Populations in southern USA and South Africa exist with males and females in segregated groups of the population

Blacktip reproduction is placental viviparity (Quiz! Do you remember what this is?), and females produce 4-11 pups per liter, with gestation lasting 11-12 months

Females have a 1 year rest after reproducing, which makes their reproductive cycles 2-years

Pups are born at 1.7- 2 feet (53-65 cm) total length

Adults reach up to 9 feet (275 cm) total length

Found near inshore waters, with inshore nursery areas, which makes this species particularly vulnerable to fishing and habitat alteration

Frequently caught in recreational and commercial fisheries

Fins are highly marketable, and meat is desirable for consumption

Known for the behavior of jumping from the water and rotating in the air

Often confused with the spinner shark, owing to this behavior and a very similar morphology!