The largest dog on record was Zeus, a donkey-size Great Dane from Otsego, Michigan, according to Guinness World Records.
At shoulder height, Zeus reached 3.6 feet. When he stood on his back legs, he towered at an impressive 7 feet, 4 inches (2.2 m), taller than most basketball players, Guinness World Records reported.
Sadly, the 155-lb. (70 kg) dog had a short life. He died at age 5 in 2014.
The lion's mane jellyfish (Cyanea capillata) can be quite small, just 0.5 inches (1.3 cm) in diameter. It can also be astoundingly large, reaching a diameter of 6.6 feet (2 m), according to National Geographic.
Its tentacles are even longer, some topping 49 feet (15 m) long, making this the largest jellyfish on the planet.
These jellyfish can also sting people. One lion's mane jellyfish reportedly stung from 50 to 100 people swimming off the coast of New Hampshire in 2010, Live Science previously reported.
The largest bat is a sight to behold. Known to some as the golden-capped fruit bat, and to others as the golden-crowned flying fox (Acerodon jubatus), it has a wingspan of up to 5.5 feet (1.7 m), according to the Encyclopedia of Life. But these giants are light, weighing just about 2.6 lbs. (1.2 kg), according to the IUCN.
The fruit bat is native to the Philippines, where it is endangered largely because of habitat loss and hunting, the IUCN reported.
It may come as no surprise that the giant squid (Architeuthis dux) is the largest cephalopod, a group that includes squid, octopuses, cuttlefish and nautiluses.
Researchers determine squid length by measuring the creatures' mantle (body length). The mantle of A. dux is more than 6.6 feet (2 m) long, but the animal's tentacles make the squid a whopping 59 feet (18 m) long in total, said Michael Vecchione, a curator of cephalopods at the Smithsonian Institution National Museum of Natural History in Washington, D.C.
The largest extinct cephalopod by shell length was the Cameroceras, which was roughly 20 feet (6 m) long. However, if you're looking at largest shell by diameter, that honor goes to the extinct Parapuzosia seppenradensis, an ammonite with a coiled shell that was 8.2 feet (2.5 m) in diameter, Vecchione said.
The eastern gorilla (Gorilla beringei) takes the prize as largest primate, with a height of up to 6.2 feet (1.9 m) and a weight of roughly 450 lbs. (205 kg), according to Gorillas-World.
These gorillas live in the mountainous forests of the Democratic Republic of Congo, Rwanda and Uganda, according to the IUCN. There are fewer than 5,000 eastern gorillas left in the wild, making them critically endangered.