The Southern Narwhal or Sea Unicorn is a tusked cetacean, reported from South Atlantic Ocean and Antarctic waters. Whale with a long tusk. Length, 10 feet.
On October 5, 1615, Dutch explorer Willem Corneliszoon Schouten noted in his journal that one of his ships was rammed by a sea monster in the mid-Atlantic. The crew later found a foot-long horn stuck in the prow.
On February 3, 1620, Augustin de Beaulieu observed a dark-blue, porpoiselike animal with a high fin and a tusk about 1–2 feet long in the South Atlantic Ocean off South Africa.
On December 17, 1892, the crew of the ship Balaena spotted a narwhal-like animal in the Bransfield Strait off the Antarctic Peninsula.
- A Swordfish (Xiphias gladius) sword looks like a tusk or horn, but the swordfish is tropical.
- An unrecognized variety of Narwhal (Monodon monoceros) that lives in Antarctic waters. Narwhals are known only from above the Arctic Circle.
- A surviving Double-tusked whale (Odobenocetops peruvianus), known from a single skull found in 1993 in southern Peru that dates from the Pliocene, 5 million years ago. Its tusks, however, pointed downward, walrus-fashion.