Octopuses are oviparous animals, which means that they lay the eggs outside their body. The female octopus’ mission is to produce viable eggs and ensure that its children successfully come out. It has two cream-colored and granular ovaries, making up 25 or 30 percent of its body mass, although it is 40 percent in some species. The male octopus inserts a spermatophore to the oviduct of the female to mate. Spermatophore opens to the nearest oviduct releasing the sperm, kept in the spermatheca until needed for fertilization. Afterward, the female searches for the place suitable for laying out the eggs. Most shallow-water octopuses place them in a den, which might be rock or human underwater structures like concrete or even beer cans. Contrastingly, some species carry their eggs with them. Mostly, the octopuses never leave their eggs and protect them.
Octopus eggs, like those of any other species, contain everything needed for the young’s development. They are tiny and surrounded by protective jelly. Interestingly, the female decides when and where to lay them. The chorion or long strand is produced to stick the eggs to the den. In general, octopuses lay from hundreds to thousands of eggs, depending on the size. Common species’ eggs are 1/8 inches in length, while deepwater animals have 1 1/2 inches long eggs. The production of young also depends on the species’ reproductive strategies, which is dictated by the rate of population and capacity of the environment. The species breeding by K-line has the danger of going extinct because producing more giant eggs and the necessity to develop slowly brings the problem of slow colonization of new territories. As a result, such species can be wiped away by some natural disaster. On the other hand, smaller species can move around faster as the water currents provide them with new settlement areas. However, they also can be hunted down in their planktonic state.
The female species die as soon as they hatch the eggs. Fortunately, they do a great job by seeking a safe place to lay their eggs. Moreover, they do not eat while guarding their eggs, which causes them to lose up to half of their weight. Despite that, it is beneficial for the eggs and females as the water quality is higher without contamination and no dangers from predators. At the end of their lives, the females turn grey and pale, because they metabolize muscles for energy. All of these processes were observed thanks to Olive the Octopus, and divers curious about the happenings. The octopuses take a long time to develop as they are growing gradually. The hatching process is a stressful experience for the young, which occurs with the help of the special gland.
The chapter is engaging the readers by describing the physiology in detail. It is extremely interesting to read because of the associations and comparisons that the author includes in the narration. In the beginning, I was confused by the biological terms the authors mentioned, but the concise explanation needed clarification. The text was neither simple nor too complicated, which undoubtedly was the reason why it was so pleasant to comprehend. I did not like the fact that the writers address similar statements multiple times, for example, the point about defending the eggs in the process of their development. I believe that a description of the investigation of Olive could be omitted as it genuinely repeats all previously mentioned points.
References
Mather, J. A., Anderson, R. C., & Wood, J. B (2013). Octopus: The ocean’s intelligent invertebrate (pp. 25-38), Timber Press.