[Biology Class Notes] on Octopus Life Cycle Pdf for Exam

The life cycle of an octopus has four stages- egg, larva, juvenile, and adult. It is a unique under-sea life cycle where the male dies within a few months of mating and the female dies soon after hatching of the eggs. 

An octopus is a soft-bodied, eight-armed marine creature which falls under Class Cephalopoda under Order Octopoda. The size of octopus varies spending on its genus. The size of the smallest octopus is around 5 cm in length while the size of the largest octopus is around 6 meters in length. The main features of octopus include a pouch-like huge head, which is slightly separated from the body, compound eyes and eight arms. A tissue, known as the skirt attaches the arms and each arm is made up of two rows of powerful fleshy suckers.  

Octopus: An interesting Undersea Creature

Reproduction, or for that matter, mating is quite a serious business for octopi the very first reason being only one per cent of around 200,000 eggs an adult octopus lay gets to survive and reach adulthood. Depending on the species, an octopus generally lives up to three to five years. They grow rapidly. Study shows, a young octopus can grow by five per cent every day, thanks to their amazing metabolic rate. Upon reaching maturity they start to reproduce. 

Each pair of male and female octopus produces only one batch of young and then dies. It’s like reproduction is the only purpose of their life. The male octopus, as stated earlier, dies usually after a few months of mating, while the female just lives to see the eggs hatching (which usually takes ten months); and after nurturing the eggs, it dies.

Systematic Position of Octopus 

Kingdom: Animalia

Phylum: Mollusca

Class: Cephalopoda

Order: Octopoda

Family: Octopodidae

Subfamily: Octopodinae

Genus: Octopus

The Life Cycle Of Octopi 

The life cycle of octopus is divided into four stages namely, the Egg (stage 1), the Larva (stage 2), the Juvenile (stage 3) and the Adult (stage 4). The four stages of the life cycle of octopus are discussed vividly in the following paragraphs:

1. The Egg (Stage 1): 

Octopi lay eggs after fertilization. The size of the eggs measures up to 0.3 cm in length. A common form of octopus such as O. Vulgaris has the ability to lay more than 10,000 eggs and the eggs are laid in small holes and under rocks. The eggs are cleaned on a regular basis with the help of the suckers until the hatching of the eggs. Female octopus saves the eggs with her life during this stage. 

2. The Larva (Stage 2): 

The hatching of eggs is done by the larval octopus after four to eight weeks of the development. The newborn larval octopi are all on their way. The newly emerged larval octopi are called octopods. They look like adult octopi and stay at the surface of the ocean. At the initial stage, octopods drift in the plankton for a long span of time before entering into the bottom of the ocean. At this stage, octopods are fed by larval crabs, larval starfish and larval lobsters. Octopods stay on plankton for a long period of time and they are fed on it in frequent manner. These larvae swim down to the bottom of the ocean after a certain point of time. 

3. The Juvenile (Stage 3): 

The juvenile octopi begin to develop at a rapid pace during this stage. The weight of juvenile octopus is increased by 5 per cent every day because of its constant feeding habits. At the last stage of the life cycle of the octopus, the weight of the octopus is one-third as much as the food it has taken. The larval octopus may enter the adult stage of its life if the circumstances are suitable. This happens because of the small life expectancy of the octopus.

4. The Adult (Stage 4): 

Octopi are sexually mature and ready to mate when the octopi enter into this stage. A modified arm known as hectocotylus is used by the male octopus to release sperms into the mantle cavity of the female octopus. The male octopi die after a few months of mating. After hatching of the eggs the female octopus also dies. Sperms can be stored for several weeks after mating by the certain species of octopi.

What Are The Characteristic Features Of An Octopus?

The octopus bears the following characteristics:

• Octopi are categorized as predators and they attack their prey by dropping down on them and enclosing it with their arms. As a result, the prey is pulled into their beaks and broken up. The beak of the octopus is similar with the beak of the parrot. 

• Octopus is rich with a brilliant sense of touch, powerful beak-like jaws and venomous saliva. They are able taste what they are touching with the help of the receptors in the suckers. 

• A very significant characteristic of the octopus is its ability to squeeze itself into surprisingly small cracks and crevices. The soft body and dearth of internal skeleton are the reasons behind this.

• There are three hearts in an octopus; two of them pumps blood to the gills and blood is circulated to the rest of the body by the third heart. 

• Octopus has blue coloured blood. The presence of haemocyanin makes the blood of the octopus blue. 

• Octopi can swim very fast. But generally, they prefer to crawl instead of swimming because the systemic heart becomes inactive and stops circulating blood to its organs at the time of swimming and thus they become very exhausted. 

• The life span of the octopus is very small. Some of the species of octopus survive only for six months. The life span of a giant octopus is about five to six years. 

• Most commonly, the octopi live at the bottom of the ocean. But sometimes they are also found on the surface of water drifting alongside planktons. They feed on large fishes, seals and whales. 

The octopus is considered as a brainiac among the invertebrates. A number of researches have been conducted on the intelligence of this sea creature. However, a lot more remains there to be studied. Nevertheless, the life cycle of octopus has a huge significance as it provides an insight into the life of oceanic invertebrates.