Today is a very special episode of Species Tuesday, as we will be discussing one of the most fascinating creatures to ever live beneath the sea: the Giant Australian cuttlefish (Sepia apama). Commonly thought of as one of the most intelligent groups of invertebrates out there, cuttlefish are members of the phylum Mollusca and are closely related to octopuses and squid. Cuttlefish and octopuses posses the highest brain-to-body mass ratio of all invertebrates, a fact that they’d be happy to point out to you while they sip Earl Grey tea and re-read Freakonomics.
The Giant Australian cuttlefish has eight arms and two longer tentacles, which it uses to capture prey and mate. It has a highly developed nervous system and incredibly advanced eyes, which can detect even low levels of light. One of the most amazing things about cuttlefish is their ability to camouflage themselves to match their surroundings, and the Giant Australian cuttlefish is no exception. This species has the ability to change the color of its skin, the texture of its skin, and the orientation of its body in order to disappear into its habitat. Oh, and it can do all of this despite the fact that it’s colorblind.
Most cuttlefish, including this Australian species, live in coastal areas where reefs, seagrass meadows, or kelp forests are abundant. They feed on mostly small fish and crustaceans, and spend a large majority of their time just laying low and hanging out. Cuttlefish and other cephalopods (squids, octopuses, and nautiluses) exhibit what is called a “live-fast die-young” lifestyle, meaning they spend a large amount of energy on their physical growth yet only live for a few years.
Because of their short life span, the Giant Australian cuttlefish typically only reproduces once in its entire lifetime. Males are extremely territorial during mating, and will guard the females vigorously. While theoretically this ensures that only the largest and strongest males reproduce, smaller males have historically been able to secure about a third of all matings through a technique I like to call “dressing up like a girl to get past the big scary guy and then charm the girl and forever lie to your friends about how you two met.” These individuals, called sneaker males, camouflage themselves like females to gain access to true females. Once there, they are able to mate with the females and force the larger males to always look for the Adam’s apple in the future.
Enjoy the Podcast!