Dolphins:
* Exceptional problem-solving skills: Dolphins can learn complex tasks, use tools, and even recognize themselves in mirrors.
* Complex communication: They use a variety of whistles, clicks, and other sounds to communicate with each other, and they even have distinct "names" for each other.
* High social intelligence: Dolphins live in complex social groups and exhibit a wide range of behaviors, including altruism and cooperation.
Cetaceans (Whales, Dolphins, Porpoises):
* Large brains: Cetaceans have some of the largest brain-to-body ratios of any animals, suggesting advanced cognitive abilities.
* Tool use: Some species, like the humpback whale, use tools like bubbles to help them catch prey.
* Culture and learning: Cetaceans exhibit cultural behaviors that are learned and passed down through generations.
Octopus:
* Exceptional memory: Octopuses have excellent short-term and long-term memory, and they can remember complex tasks.
* Problem-solving: They are known for their ability to solve puzzles and escape from confined spaces.
* Camouflage and mimicry: Octopuses are masters of camouflage and mimicry, which suggests advanced cognitive abilities.
Other contenders:
* Fish: Some fish, like the wrasse and the parrotfish, show signs of learning and problem-solving.
* Sea turtles: Sea turtles are known for their navigation skills, which require complex cognitive abilities.
Ultimately, determining the "smartest" sea animal is a matter of opinion and depends on how you define intelligence. However, the sea is full of fascinating creatures with impressive cognitive abilities.