Sperm whale

The Sperm whale (Physeter catodon) is believed to be the largest toothed animal living today on earth. It has gotten its name because scientists thought they found a milky white substance in its head and they mistakenly thought it was sperm, although actually it was a kind of whale oil. A male sperm whale's head is about one-third of its total length. The part of its scientific name "macrocephalus" means "long head". The brain of this magnificent animal is the largest ever recorded: 7 kg! The tail (see picture) is triangular in shape and lifted very high when going for a deep dive...

Some world records of the Sperm Whale:

1. Largest known toothed creature ever.
2. Deepest dive by a mammal (sperm whales have been found in depths of 2,200 (7,200 feet) meters, tangled in telegraph cables).
3. Largest brain of any living creature on Earth. The brain of a mature sperm whale weighs 7 kg (15 pound), though there have been specimens with 9 kg (20 pound) brains.
4. Thickest skin. On back and head, sperm whale's skin (not including subcutaneous fat) is sometimes up to 35 centimeters (14 inches) thick.

   (source Wikipedia)