Question

On the article called Deep-Sea Octopus (Graneledone boreopacifica)
Conducts the Longest-Known Egg-Brooding Period of
Any Animal
By Bruce Robison1*, Brad Seibel2, Jeffrey Drazen3

What advantage does it give for a species to have a long egg-brooding period as opposed to a short one?

How would the number of offspring differ for long-egg brooding versus short-egg brooding species?

Answer 1

Question 1: What advantage does it give for a species to have a long egg-brooding period as opposed to a short one?

Answer:

According to the article titled "Deep-Sea Octopus (Graneledone boreopacifica) Conducts the Longest-Known Egg-Brooding Period of Any Animal", species that have a longer egg-brooding period can produce hatchings that are highly developed and has a better chance at survival in addition to an extension of the lifespan of an adult. The main reason for this is the lower temperatures of the deep sea.

The observation of the G. boreopacifica female over the course of 53 months has shown that the prolonged brooding period gives rise to a better-developed hatchling. Deep-sea octopodid cephalopods generally use a holobenthic reproductive strategy which ensures that the embryo directly develops without a larval stage and makes sure the hatchlings are developmentally advanced. Most deep sea-dwelling cephalopods skip the larval stage because they cannot withstand the pressure and temperature of the deep sea. A quick look at the Fig. 6 which graphically represents the relationship between development time of the octopodid cephalopods hatchlings in days and the temperature shows that it is inversely proportional. Lower temperatures lead to longer development time whereas higher temperatures lead to shorter development time. The result is that longer developmental times ensure a highly developed mini adult hatchling that has a higher survival rate. This is mostly absent in species with shorter brooding times.

Another interesting advantage of a longer brooding period is that it gives a longer lifespan to the females so that it could care for the egg. A female octopod spends nearly a quarter of its lifespan brooding over her eggs. Although this period is spent in inactivity that results in the organism wasting away and eventually dying.

Thus a longer brooding period is advantageous in the production of highly developed offsprings in lower temperatures.