Cirrate octopods, cephalopods
known as the dumbo octopuses
are among the largest invertebrates of the deep sea. These organisms have long been known to lay single, large egg capsules on hard substrates on the ocean bottom, including cold-water octocorals. Although
juveniles have previously been collected
in the midwater, cirrate hatchlings
have so far never been observed. However, researchers has been able to locate a dumbo octopus eggs in a submarine mountain at 1,900 m, and have discovered that they look and act like adults from the moment they hatch.
The egg capsule is comprised of an
external egg case as well as the chorion
and developing embryo. Development
in cirrates proceeds for an extended
time without parental care
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Dumbo octopus hatchling, with opened egg case attached to octocoral Chrysogorgia artospira collected at 1,965 m depth on Kelvin Seamount, Atlantic Ocean.
The baby dumbo octopus behavior shows that cirrate hatchlings possess all morphological features required for movement via fin-swimming, for visually and chemically sensing their environment, and for prey capture. The presence of a large internal yolk sac reduces the risk of failure at first feeding. This is enough evidence that dumbo octopods hatch as competent juveniles.
Cold-water octocorals appear to be critical in cirrate life cycle, and their destruction by bottom trawling or mining will impact populations of mobile animals like the charismatic dumbo octopods
