The animal that does not pee are birds.
Instead of peeing birds convert nitrogen to uric acid instead: this is metabolically more costly but saves water and weight, as it is less toxic and doesn't need to be diluted so much.
Birds therefore don't have a urethra, and don't pee - all waste leaves via the anus.
The animals that have the highest number of heart are the octopuses and squid.
The octopus has multiple hearts, and that fact can reveal secrets about their evolutionary history while also informing our understanding of how they manipulate their environments.
There are three hearts beating inside octopuses and squid: one main heart that pumps oxygenated blood through the entire body and two branchial hearts that specifically pump blood through the gills to the main heart for oxygenation.
The animals that have blue blood include Lobsters, crabs, pillbugs, shrimp, octopus, crayfish, scallops, barnacles, snails, small worms (except earthworms), clams, squid, slugs, mussels, horseshoe crabs, most spiders.
The animal that has no brain are sponges.
Sponges are simple animals, surviving on the sea floor by taking nutrients into their porous bodies.
Jellyfish also have no brain or heart.
Jellyfish do poop although they don't poop out of an anus.
Jellyfish actually poop out of their mouth which is the same place where they take in food.
Jellyfish expel waste through the same hole where they take in food.
Jellyfish are more colorful and fascinating to look at than flatworms, but they are similar in their excretion of waste.
Most animals have two holes, one for a mouth and one for an anus.
Not so with these mysterious creatures!
The first animals that arose seem to have literally had potty mouths: Their modern-day descendants, such as sea sponges, sea anemones, and jellyfish, all lack an anus and must eat and excrete through the same hole.
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria.
Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile.
The bell can pulsate to provide propulsion for highly efficient locomotion.
Box jellyfish, named for their body shape, have tentacles covered in biological booby traps known as nematocysts - tiny darts loaded with poison.
People and animals unfortunate enough to be injected with this poison may experience paralysis, cardiac arrest, and even death, all within a few minutes of being stung.
Lacking brains, blood, or even hearts, jellyfish are pretty simple critters.
They are composed of three layers: an outer layer, called the epidermis; a middle layer made of a thick, elastic, jelly-like substance called mesoglea; and an inner layer, called the gastrodermis.
Some interesting facts about Jellyfish are.
Some jellyfish can glow in the dark.
Jellyfish are the oldest multi-organ animal.
Jellyfish are found all over the world.
Some jellyfish are immortal.
Not all jellyfish have tentacles.
There's a giant jellyfish called the hair jelly.
150 million people are stung by jellyfish each year.