Octopus moms seek the heat

This exercise is a part of Educator Guide: Deep-sea ‘Octomoms’ Seek the Heat / View Guide

Directions for teachers: Ask students to read the online Science News article “Some deep-sea octopuses aren’t the long-haul moms scientists thought they were,” and answer the following questions. A version of the article, “Deep-sea ‘octomoms’ seek the heat,” appears in the April 9, 2022 issue of Science News.

1. What is the Octopus Garden? Why is it called that?

The Octopus Garden is a patch of seafloor 3,200 meters deep off the coast of California where deep-sea octopuses congregate. It’s called a “garden” because many of the animals there are octopus moms caring for their developing eggs.

2. What did scientists predict about the brooding period in the octopus garden and why?

Scientists thought brooding in the garden would take a very long time, perhaps a record-setting 12 years. Embryonic development tends to slow down in low temperatures, and temperatures in the garden are only about 1.6° Celsius.

3. What data did scientists collect to try to verify their predictions?

Scientists observed the octopuses and their eggs with cameras and took water temperature measurements in nests.

4. What tools did they use to collect that data? Why?

Scientists used remotely operated vehicles with robotic arms because this area of the seafloor is otherwise inaccessible and hard to observe directly.

5. What did the collected data ultimately reveal? List at least two findings.

Water temperatures in the nests were warmer than expected, up to 10.5° Celsius. Also, brooding lasted for about 600 days, or a year and a half.

6. What did researchers conclude based on these findings?

The researchers concluded that octopuses are laying eggs in the warmer water of geothermal springs, which is speeding up embryonic development and thus reducing brooding time.

7. Why is a shorter brooding period beneficial from an evolutionary perspective?

Reducing the brooding time reduces the risk that predators will eat octopus eggs.

8. Are octopus moms the only animals that seek out warm waters for breeding? Explain.

No. A few other animals, including icefish, do it too. The scientists suspect other species probably take a similar approach.