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from not having to breathe to having to expel liquid from our lungs and drawing our first breath. Through the course of vigorous muscular contractions, we are expelled out the birth canal into the external world, much like other mammal babies. Chickens and other birds have to chip their way out of their tough eggs. Frequently the chicks have a hatching tooth that helps them penetrate the eggshell, which is later resorbedor falls off as the chick grows up. Some reptile mothers such as crocodiles help the eggs hatch by gently cracking the eggs, and mother octopuses may also help the eggs hatch.
    Octopus hatching occurs with the aid of a hatching gland, a collection of enzyme-containing cells on the mantle of the embryo that help dissolve the chorion (egg shell), along with violent expansions and contractions of the mantle. The little octopus paralarva breaks mantle-first through the distal end of the egg, popping out in the normal swimming posture of a jetting octopus. The octopus lives on a remnant of its yolk sac for the first few days, but that is soon absorbed, and the hatchling must find food for itself. Benthic hatchlings, like those of the Caribbean reef or Californian two-spot octopus, just crawl away, but paralarvae of species such as the red octopus take up the life style of a drifter, swimming in the rich surface waters of the sea.

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    Drifting and Settling
    W hile most octopuses live on the sea bottom, the situation is different for the newly hatched young. The many species of octopuses have two different life style strategies as hatchlings. These differences come from the size of the eggs, not the size of the adult animals: the giant Pacific octopus is one of the biggest octopuses but has tiny young. Most octopus species lay small eggs that produce small baby octopuses that are planktonic—they get washed away by ocean currents and temporarily live in the plankton-rich surface waters of the ocean. A few species lay large eggs that produce benthic hatchlings, big enough to live on or near the bottom of the ocean.
    Living in the plankton requires adaptations, especially for the early stages of an animal like the octopus that later spends its adult life crawling on the bottom of the ocean among the rocks or coral. To understand why many young octopuses start their lives in the plankton, we must understand what plankton is, how the plants and animals that comprise plankton live, what methods they use to keep from sinking, what they eat, how they swim, what preys on them, and how they avoid being eaten. We must understand the advantages and disadvantages of living in the plankton, the bigger ecological implications of having a life stage different from that of an adult, and the adaptations and changes needed to live that life stage in that environment.
    The word “plankton” is derived from the Greek root word that means free floating or wandering. The term is applied to any plant or animal that is unattached and floating in the surface waters of the ocean as well as to any weak, swimming animal that cannot swim against the ocean’s currents. Even some comparatively large creatures such as jellyfish and the open-ocean argonaut octopus are part of the plankton. Relatively huge creatures such as sea turtles and ocean sunfish, which are weak swimmers, are sometimes considered planktonic. Plankton includes marine bacteria,animals, and plants, and some swimming animals that have plant pigments that undergo photosynthesis (making food from carbon and oxygen), which is normally a plant trait.
    In her poem Plankton, Joan Swift wrote:
    They live their lives unseen
    Not just gray mobs without faces
    But like calm, steady workers
    In some underground plot
    To keep the world alive.
    Plankton does indeed keep the world alive and is pretty much unseen and under-appreciated.
    Animals and plants living in the plankton are the most important organisms in the ocean, but they are neither the most visible, the best known,