120 Sharks: The Animal Answer Guide
Skate incubation periods are highly dependent on temperature; babies
develop more quickly at warmer temperatures. Thorny Skate incubation
can take as little as a couple of months to as long as a year. Little Skate eggs
may hatch in 6 to 9 months in Connecticut waters but may take a year to
hatch farther north in Maine.
Hatching times for chimaeras are known for two species, the Australian
Elephant Fish and the Spotted Ratfish. Hatching appears to take between 5
and 12 months, the shorter time applying to the Australian Elephant Fish.
The baby chimaeras that emerge from these eggs are about 10 to 15 cm
long (4–6 in).
Where do sharks lay their egg cases or give birth?
Many elasmobranchs leave their normal habitats to give birth or lay
eggs. Females usually move into shallower water, often near shorelines.
Bluntnose Sixgill Sharks (Hexanchus griseus) commonly occupy oceanic
depths of 500 to 1,500 m (1,650–5,000 ft). Pregnant females move into
shallow Puget Sound, Washington, and juveniles are fairly common at
depths of less than 30 m (100 ft). Broadnose Sevengill Sharks are a coastal
species that occurs to depths below 100 m, but females move into shallow
areas of Humboldt and San Francisco bays to give birth. Lemon Sharks
frequent shallow reef areas but move into even shallower mangrove forests
to give birth. Scalloped Hammerheads are well known for migrating to
and from oceanic seamounts near deep water; even so, they give birth in
shallow regions of the Gulf of California and Kaneohe Bay, Oahu Island,
Hawaii. Scalloped Hammerheads and Smooth Hammerheads (S. zygaena)
move into the innermost sections of Ariake Bay in southern Japan in sum-
mer to give birth. This same shallow section of Ariake Bay is a nursery area
for four shark and eight ray species.
Female Leopard Sharks and Whitetip Reef Sharks also move into shal-
low, warmer bays before giving birth. It has been suggested that by moving
into areas with higher water temperatures, females increase the growth rate
of their developing pups; the larger and presumably faster pups would then
be better able to find food and avoid predators.
Some holocephalan chimaeras also move inshore to reproduce. Rab-
bitfish normally inhabit Atlantic waters at depths between 300 and 1,250 m
(990–4,125 ft) but migrate in spring and summer to water less than 100 m
(330 ft) deep to lay eggs. Australian Elephant Fish also migrate inshore to
shallow water bays during their summer-to-autumn egg-laying season and
then move back offshore in winter and spring.
Because most larger sharks live in deep water offshore, it is assumed
that by giving birth in shallow nearshore areas, females are reducing pre-
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