In 2018, scientists discovered an immense aggregation of Muusoctopus robustus (pearl octopuses) along a hydrothermal vent 3,200 meters beneath the ocean’s surface. Water temperatures at this site—named the Octopus Garden—climb as high as 11°C, much warmer than the ambient 1.6°C typical at this depth. Based on observations made over three years, scientists concluded that temperatures at the site likely confer reproductive benefits and that the site is used exclusively for reproduction—6,000 M. robustus adults, hatchlings, and eggs were observed at the garden, but no juveniles were present.
Which statement about M. robustus and the Octopus Garden is best supported by the text?
Explanation
Context: At the Octopus Garden, a warm hydrothermal vent site thousands of meters deep, three years of observation turned up 6,000 M. robustus adults, hatchlings, and eggs but no juveniles, and scientists concluded the site is used exclusively for reproduction. The question asks what this supports.
Answer: D) M. robustus leave the Octopus Garden upon reaching an intermediary stage of development.
Why? Juveniles occupy the stage between hatchling and adult, and three years of observation found none while the stages on either side were abundant. The young must depart once they outgrow the hatchling stage and return only to breed.
Traps:
- A) Temperatures are compared with ambient conditions at depth, but no population count over time or across temperature swings is reported.
- B) The site is described as serving reproduction exclusively, and feeding is never mentioned.
- C) No egg counts or sizes are given, and no nests at other depths are compared.