These intelligent cephalopods have evolved a remarkable circulatory system. Two hearts pump blood to the gills, while a third maintains circulation to the organs. When swimming, the organ heart stops beating, which is why octopuses prefer crawling. Their blood is blue due to hemocyanin, a copper-based protein that's more efficient than hemoglobin in cold, low-oxygen environments.

These pink birds have one of the most colorful collective nouns in the animal kingdom. Their distinctive color comes from carotenoid pigments in their diet of algae and crustaceans. Interestingly, flamingo knees are actually their ankles - what appears to be their knee is actually their wrist joint!

The basilisk lizard, nicknamed the "Jesus Christ lizard," can sprint across water surfaces for distances up to 20 meters. They achieve this through rapid slapping motions with their large feet that create air pockets, combined with their light weight (about 200 grams) and high speed (1.5 meters per second).

Research shows cows form close friendships with 2-4 preferred companions. When separated from these friends, their heart rates increase and they show signs of stress. This social bonding is crucial for their well-being and even affects milk production.

Dolphins develop unique signature whistles that function like names. They can recognize these whistles even when played back through computer synthesizers, demonstrating complex communication skills. Dolphins will also sometimes mimic the signature whistles of absent companions, possibly "calling" them.

Leafcutter ants cultivate fungus gardens, making them one of the few animals besides humans that farm. They use freshly cut leaves as fertilizer for their fungal crops, which serve as their primary food source. This symbiotic relationship has existed for about 50 million years.

The Turritopsis dohrnii jellyfish can revert to its polyp stage after reaching maturity, essentially resetting its life cycle. This process can theoretically continue indefinitely, making it the only known biologically immortal animal. However, most still die from predation or disease.

Modern birds are direct descendants of theropod dinosaurs like Velociraptor. Key evidence includes:

• Similar skeletal structures
• Feathers found on many dinosaur fossils
• Nesting behaviors preserved in fossil records
• Some dinosaurs had wishbones (furcula) like birds

The largest animal ever known to have existed has equally impressive anatomy:

• Heart weighs about 400 pounds (180 kg)
• Aorta is large enough for a human to crawl through
• Heart beats just 2-10 times per minute when diving
• Can be heard from 1,000 miles away

This small crustacean has one oversized claw that snaps shut with such speed (60 mph in under 1 millisecond) it creates:

• Cavitation bubbles that reach 4,700°C (briefly hotter than the sun's surface)
• Underwater shockwaves that stun prey
• One of the loudest sounds in the ocean (218 decibels)