Reproduction and Development 125
What is a baby shark called?
The young of many bony fishes are called fry, and some have special
names—alevins, parr, and smolt in salmon; elvers in eels; and ammocoetes
in lampreys. In addition, many bony fishes have very small larvae that are
very different from the adults, and these larvae have their own names. But
shark babies are miniature adults, not distinct larvae. Baby sharks are usu-
ally called pups.
Are all the baby sharks in a mother full siblings?
Given the variability of reproductive behavior and development among
sharks, it isn’t surprising that the answer to this question is yes and no. Pa-
ternity analysis (identifying the father) has been attempted only for a small
number of species, but the results show the complete range of possibilities.
Bonnethead Shark pups are usually full sibs, fathered by the same male,
although occasionally multiple fathers are involved in the case of larger
females that are carrying larger litters. Litters of Lemon Sharks have more
than three fathers. Other species analyzed include Spiny Dogfish (two fa-
thers), Nurse Sharks (more than four fathers), Shortspine Spurdog (usually
only one), Bignose Shark (more than two), and Sandbar Shark (two to five).
A Bluntnose Sixgill Shark that washed ashore near Seattle, Washington,
contained 80 embryos. DNA tests showed that eight different males had
fathered the babies, thus far a record number among elasmobranchs. Tag-
ging studies suggest that although a litter may have several fathers, litter-
mates remain together in Puget Sound for extended periods.
Even egg-layers appear to mate with several males each cycle. More
than 90% of female Small-spotted Catsharks studied had mated with sev-
eral males.
This small sample of species suggests that many if not most shark fe-
males mate with several males during each breeding season. One strong
exception to this generalization is the Whale Shark. Twenty-nine embryos
taken from a litter of 304 found inside one female Whale Shark showed a
complete range of developmental stages and sizes. Despite this range, all
the young were full sibs sired by the same father. This would indicate that
female Whale Sharks can store sperm and produce eggs over a long period,
allowing the eggs to be fertilized at different times.
Do sharks care for their young?
Yes, but only before birth. No sharks, skates, rays, or chimaeras are known
to care for their young once a baby is born or an egg is laid. The actual “care”