Octopuses capture the imagination with their remarkable intelligence, unique biology, and enigmatic presence in marine environments. Their ability to solve problems, change color, and navigate complex spaces makes them subjects of widespread interest. The early life stages of these fascinating cephalopods present a distinct chapter in their development, differing significantly from their adult forms.
Their Names
While commonly called “baby octopuses,” the scientific community uses more precise terms for these young cephalopods. The most prevalent term for a newly hatched octopus is “paralarva.” Unlike many other animal larvae, octopus paralarvae do not undergo complete metamorphosis; instead, they grow morphometrically, changing proportions as they develop. “Hatchlings” is another term used to describe octopuses immediately after emerging from their eggs.
Distinctive Features
Octopus paralarvae are remarkably small upon hatching, often measuring only a few millimeters. Their bodies are frequently transparent or translucent, a characteristic that aids in their survival in the open ocean. Initially, their features are relatively undeveloped compared to adults, with arms that may be proportionally shorter and fewer suckers.
Despite their diminutive size, these paralarvae are equipped with specialized pigment cells called chromatophores, which allow them to change color for camouflage. They hatch with a limited number of large chromatophores, and additional, smaller ones develop as they grow. A unique feature of paralarvae, not found in adults, are transient epidermal structures known as Kölliker’s organs. These bristle-like organs cover their bodies and are believed to play a role in buoyancy or possibly in the hatching process, eventually disappearing as the octopus matures.
Life in the Open Ocean
Octopus paralarvae begin their lives in the pelagic zone, inhabiting the open ocean water column, often near the surface. This contrasts sharply with the benthic, or bottom-dwelling, lifestyle of most adult octopuses. Their diet during this planktonic phase consists primarily of zooplankton, including small crustaceans. Maintaining their high metabolic rates requires a consistent supply of appropriately sized and nutritionally rich live prey.
Life in the open ocean presents numerous challenges for these tiny creatures. They face significant threats from predators, contributing to high mortality rates in this early stage. Nutritional deficiencies and even cannibalism among paralarvae are also known issues. Movement for paralarvae often involves passive drifting with ocean currents, though they can employ jet propulsion for more directed swimming. The duration of this pelagic stage varies by species and environmental factors such as temperature, lasting weeks to several months, before a transition known as settlement occurs as they adapt to a benthic adult habitat.