What is the largest animal without a back bone
Answers
The colossal squid (Mesonychoteuthis hamiltoni, from Greek mesos (middle), onycho (claw, nail), and teuthis (squid)), sometimes called the Antarctic squid or giant cranch squid, is believed to be the largest squid species in terms of mass. It is the only known member of the genus Mesonychoteuthis. It is known from only a few specimens, and current estimates put its maximum size at 12–14 m (39–46 ft) long and weighing possibly up to 750 kilograms (1,650 lb),[3][4] based on analysis of smaller and immature specimens, making it the largest-known invertebrate.
The species was first discovered in the form of two tentacles found in the stomach of a sperm whale in 1925.[14] In 1981, a Russian trawler in the Ross Sea, off the coast of Antarctica, caught a large squid with a total length of over 4 m (13 ft), which was later identified as an immature female of M. hamiltoni.[15] In 2003 a complete specimen of a subadult female was found near the surface with a total length of 6 m (20 ft) and a mantle length of 2.5 m (8 ft 2 in).[16] This specimen shows that colossal squids may grow larger than 500 kg (1,100 lb), possibly up to 750 kg (1,650 lb).[3]
In 2005 a specimen was captured at a depth of 1,625 m (5,331 ft) while taking a toothfish from a longline off South Georgia Island. Although the mantle was not brought aboard, the mantle length was estimated at over 2.5 m (8 ft 2 in), and the tentacles measured 2.3 m (7 ft 7 in). The animal is thought to have weighed between 150 and 200 kg (330 and 440 lb).[17]
The largest recorded specimen was captured in 2007 by a New Zealand fishing boat off Antarctica. It was initially estimated to measure 4.5 m (15 ft) in length and weigh 450 kg (990 lb). The squid was taken back to New Zealand for scientific study.[18] A study on the specimen later showed its actual weight was 495 kg (1,091 lb), but it only measured 4.2 m (14 ft) in total length as a result of the tentacles' shrinking post mortem.