Page 161 - Design in Nature

Smooth skin Dolphin skin
Flow of water

Social Life of Dolphins
Dolphins live in very large groups. For protection, females and
offspring are located in the centre of the group. The sick are not left alone
but are kept in the group until they die. The ties of interdependence are
formed from the first day a new offspring joins the group.
Dolphin calves are born tail first. This way the infant is provided with
oxygen throughout delivery. When at last the head is released, the newly
born dolphin rushes for the surface for the first gasp of air. Generally, during
delivery another female accompanies the mother giving birth.
Mothers start to nurse their young immediately after birth. The new
dolphin, lacking lips to suck, receives milk through two
sources coming out of a slit on the mother’s
ventral surface. When it taps gently on this
section, the milk is sprayed out. The
young dolphin consumes dozens of
quarts (litres) of milk every day. 50% of
the milk is composed of fat (compared to
15% in cattle milk), which promptly works
towards building the skin layer necessary to
regulate body temperature. Other females also help the young
dolphins during rapid dives, by pushing them down. Newly born dolphins
are also taught how to hunt and use their echolocation sonar, which is an
educational process continuing for years. In some cases, young dolphins
may never leave a particular family member for up to thirty years.

The System Preventing the Bends
Dolphins can dive down to depths that cannot be matched by humans.
The recordholder in this category is a species of whale that can dive down
to 9900 feet (3000 metres) on a single breath. Both dolphins and whales are
created appropriately for these kinds of dives. The tail flukes make diving
and surfacing much easier.
Another aspect of the design for diving is in the lungs of these animals: