Fur and hair are two totally different things. They differ in growth pattern, composition, look, etc. There are some species of animals that have hair, rather than fur. A detailed description of the two can be found at the website listed below in Related Links.
According to Guinness World Records the Sea Otter has the densest fur with 100,000 hairs per cm2
The sloth
Well this will sound crazy but it is us humans. We can have the longest hair in the animal kingdom. I believe the longest is 18 ft 5.54 inches. I believe the second longest hair in the animal kingdom would probably be a horse. There tail can be very long. http://www.guinnessworldrecords.com/records/human_body/extreme_bodies/longest_hair.aspx
Kate longwell
giraffe
The longest person in the world that has the longest armpit hair was Iwokasha Ban from Iraq who had arm pit hair like an ungroomed.
The longest hair on a horse is its tail, but the longest mane in the world records was nine feet and ten inches.
Cindy Christensen
The longest animal in the world is the bootlace worm, it can be found along the coast of Britain. See related link for more detail..
Seabirds
The longest animal in the world would be the bootlace worm (Lineus longissimus). A specimen was recorded at 180 feet long. The longest vertebrate in the world is the Blue Whale (longest recorded at 108ft).
Guiness Book of World Records would have that info.
The Sperm Whale (Physeter Macrocephalus) (Cachalot) is the animal with the longest skull in the world (both in general and aquatically). The African Bush Elephant (Loxodonta Africana) is the longest-skulled terrestrial animal in the world. The extinct aquatic animal with the longest skull would probably be either a Mosasaurus Hoffmannii or a Carcharodon Megaladon. The Titanoceratops Ouranos is the extinct terrestrial animal with the longest skull.