The Underwater Costume was a part of an Account Upgrade from July 2006 and is now retired. If you put this on your pet, they will become a sea creature in order to fit in with their Underwater surroundings. The costume is green with scales, water, and a green fish. View the old pets here and here.
Unsurprisingly, the Underwater Chibs is based on the catfish. Catfish comprise the Siluriformes family, a group of freshwater and coastal bottom-dwelling fish found around the world. Most catfish sport the distinctive whisker-like barbels for which they are named, which allow them to taste and smell their environment. In addition to being farmed for food, some species, including the Corydoras which likely served as the model for the Underwater Chibs are raised as ornamental aquarium fish.
Underwater Dakotas look like manta rays. Manta ray "wing" spans can be up to 20 feet, allowing them to fly through the water like birds. They mostly live in the tropical region of the ocean, from north Mexico to South Chile. There are no predators to the manta ray other than large sharks, and they are a small threat to humans, eating only plankton.
The Underwater Ercuw is most probably based on the sea dragon, which is related to the sea horse. They have random appendages that camouflage them in the kelp and other plants. Sea dragons move very slowly and are found mostly around Australia. They are rather rare and could become endangered if aquariums continue capturing them. A fully grown sea dragon is about 18 inches long and they live for about 2 years.
The Underwater Eyru looks very much like a goldfish. The goldfish was one of the earliest fish to be domesticated and is one of the most commonly kept aquarium fish today. Part of the carp family, the goldfish is, more specifically, a domesticated version of a less-colorful carp native to east Asia. Overall... pretty low-radar fish.
As you may have guessed, the Underwater Gobble is a puffer fish! Puffer fish inhale large amounts of water and "puff" themselves up to ward off a predator. There are over 150 known species of puffer fish in the world. They are extremely poisonous and can give off a poison that disrupts the nervous system. Despite this, they are a delicacy in Japan, and only registered chefs that have undergone a special test can prepare them for consumption.
The Underwater Ideus is a red lionfish, and its venomous dorsal spines are used purely for defense. When threatened, the fish often faces its attacker in an upside-down posture which brings its spines to bear. However, its sting is usually not fatal to humans. If a human is envenomed, that person will experience extreme pain, and possibly some side effects. A common treatment is soaking the afflicted area in hot water, as very few hospitals carry specific treatments. However, immediate emergency medical treatment is still advised, as some people are more susceptible to the venom than others.
This Underwater Kujo here resembles a dolphin. People enjoy watching dolphins play and jump for air. Dolphins frequently leap above the water surface for various reasons. When travelling, jumping can save their energy as there is less friction while in the air.
The Underwater Leido is, I think, one of the more impressive Underwater pets. The sea turtle, which the Underwater Leido was taken from, does have the same flippers which substitute the Leido's feet so well. When sea turtles lay their eggs, they lay them on the shore and bury them in the sand. Once the turtles hatch, they crawl back into the sea to brave the deep waters and grow into adults. Only about 1/5 of the hatchlings laid make it back to the sea, though.
The Underwater Limax is likely influenced by the chromodoris willani of the nudibranch - another way of saying a blue sea slug! This species can be distinguished by its very prominent white specks found on the gills and rhinophores. Individuals in this species can range in color from dark blue to a translucent white. All have black stripes with the center-most stripe typically being non-continuous. Many of them can also release acid or toxins from their skin, just in case the predators manage to find them!
Everyone's had some pet sea monkeys, right? Well then you're sure to recognize the Underwater Quell! Sea monkeys are just novelty aquarium pets. The name was based on the supposed resemblance of the animals' tails to those of monkeys, and their salt-water habitat.
While at first glance the Underwater Raulf appears to be based on an eel, astute Maradans have pointed out that it in fact more closely resembles the Giant Oarfish, particularly with its unique colors. These fish have been known to grow upwards of 36 feet long, and are believed to be the source of many "sea serpent" sightings.
We'll analyze the Underwater Sybri. It is, indeed based off of the common seahorse. There are 32 species of seahorse in the world. The largest species is 30 cm, or around 1 foot, in length. All sea horses belong to the genus of hippocampus (scientific classification), which relates to a Greek creature called the Hippocampus.
The Underwater Tantua is based off the sea lion, but this looks like a literal sea lion, hence the mane and fur on the tail, Tantuas are most likely your Maradan of the sea lion.
The Underwater Ushunda is based on the common octopus. Octopodes usually have 8 tentacles with suckers that they use to cling to things and help them move around or catch prey. They're usually shy and only come out at night. The common octopus can grow to about a meter in length. When they are scared or startled, octopodes can eject dark ink into the water so they can escape.
The Underwater Zetlian... the terror of the deep... Great White Sharks are an average length of 15 feet, and have teeth that are as sharp as a regular kitchen knife. Capable of detecting electrical fields that us humans give off and being able to literally smell out its prey, the Great White Shark is a formidable creature of the deep. You don't want to meet up with an Underwater Zetlian while taking a swim at the beach!
The oldest Underwater Gobble resembled an Eothyris. Other than that, it does not appear to be directly based off of any sea creature. If you have an idea of what Marapets' inspiration was - let us know! Note: We've already ruled out all Synapsids so please consider that before sending in tips! Thanks =)