benthic (paleo)ecology, ichnology, paleobiology
If I could have another life as an invertebrate, I would certainly choose to reincarnate as a cephalopod. Just in case that choice is not obvious to you I will give you my seven reasons:
1. To be smart
Cephalopods have the largest brains among invertebrates and they, particularly octopuses but also squids and cuttlefish, have proven their capability to learn and retain information in numerous tests and observations. Some may even argue that they are capable of using tools (see video of the California Academy of Sciences below).
2. To be huge
Although not all cephalopods are large, the group includes enormous monsters. The great Jules Verne portraited a dreadful giant squid in his novel ‘Twenty thousand leagues under the sea”. These animals actually exists (genus Architeuthis). They inhabit the deep ocean and it is thought that some may reach 15 m in length (including the long tentacles) or even more. Giant cephalopods also lived in the ancient oceans of Earth and they are well know from their fossils, such as some extinct straight-shelled nautiloids and coiled-shelled ammonites (picture below).
3. To have many arms
The term cephalopod derives from the Greek words for head and feet. All members of the group have numerous muscular appendages, 8 in octopuses, 10 in cuttlefish, near one hundred in nautilids. They employ their tentacles to interact with the environment, for feeding, locomotion and sexual purposes. Imagine what could you do with so many versatile arms.
Cephalopods are carnivorous. Many are active predators and some scavengers. I like seafood so this is a very yummy reason.
5. To have beautiful (and efficient) eyes
Cephalopods have two eyes, as we do. They are highly sophisticated (except in Nautilus) and provide them with an excellent and acute sight essential for their life activities. Apparently some are color blind, but that is not a real problem for me as I proudly am too.
6. To have a long and exciting family history
Cephalopods have swam the oceans of this planet for near 550 million years. The fossil record of those that had a mineral skeleton (external or internal) is abundant and demonstrates their importance as key players of ancient marine ecosystems. The diversity of groups is important including typically Paleozoic forms such as orthoceras (below), bactrictes or goniatites, and Mesozoic groups such as ceratites, ammonites or belemnites. Most of these shelled forms went extinct and only nautilids survive till today. These groups together with the variety of unshelled extant taxa (whose fossil record is scarce due to its lower preservation potential) put together an extensive and diverse family tree. Something to be proud of.
7. Not to need a pen anymore
Most cephalopods bear a gland capable of producing dark ink, which is released as a defense mechanism when threatened by predators. The ink contains chemicals that affect the sense of smell and taste of the attackers and may serve to alert other cephalopods.
There are many more reasons that could be added – floating relaxed in the sea water, enjoying marine life, no sweating,… – but the seven above are probably more than enough, particularly considering that I have no real plans to reincarnate, at least in the short term.