The sand tiger shark (Carcharias taurus) is the only shark known to gulp air at the surface. It keeps the air in its stomach, which improves its buoyancy. The female is ovoviviparous, its eggs hatch inside of her and feed on the eggs it keeps on producing. After nine months to a year, two pups of about one meter long are born. The sand tiger shark feeds mainly on fish and no attacks on humans have been recorded so far.