We know almost nothing about Giant Squids with mantles lengths less than 1000 mm (~40 inches). Very young squids are even more enigmatic than adults. A recent study reports the collection of three very young Giant Squids off the Japanese coast. The three young measured 140.8, 332, and 332 mm (5.5 and 13 inches). The heaviest of the three weighed less than pound (390.6 g). Unlike the adults the fins of the juveniles were quite tiny compared to the length of the body. In juveniles the length of the tentacles were just a slightly longer than the body. In adults Giant Squids where the length of the tentacles can be over 3 times the length of the body. With adulthood comes massive fins and tentacles!
Wada, T., Kubodera, T., Yamada, M., & Terakado, H. (2015). First records of small-sized young giant squid Architeuthis dux from the coasts of Kyushu Island and the south-western Sea of Japan Marine Biodiversity Records, 8 DOI: 10.1017/S175526721500127X