The Ancestor’s Tale, Rendezvous 26: Protostomes Part 3 (Peanut worm)
The Ragworm’s Tale: Creative Thought Experiment
At the risk of upsetting the author of the book, let’s pretend we’re some ultimate deity (Evolica: goddess of evolution). Let’s say you want to “create” a sea worm. Let’s start with the familiar cylindrical shape. What are some considerations we have with our living cylinder?
1) Worm’s gotta eat! Some way of getting outside nutrients in it’s body. Give it a hole (for now let’s just put it anywhere).
2) There may be bad things that enter the worm, along with waste that doesn’t need to be in the worm anymore. It could come out the same hole it came. But that could be problematically untidy (don’t shit where you eat). Maybe let’s make another hole. Maybe we want that second (waste) hole as far away from the food hole as possible. The most efficient way is on opposite sides of the cylinder. Our arbitrarily placed food hole is now moved to a the side we decide to call the head.
3) We don’t want a stationary worm, There’s likely an energy profit (energy gain-energy used) to finding food. Which direction will this worm move/swim? There are many choices in our infinite power, but it’s probably most efficient to move and/or swim forward (head first).
4) While it’s probably doing well blind, seeing would probably increase efficiency. Let’s give the worm some eyes. How many and where? Where is easy. On the head. But above or below the mouth? If this worm was on the ground, above it would be water and below would be ground. Considering eye irritation as well as larger perception, let’s give it above-mouth eyes. How many? Aren’t two eyes better than one? Wait! Aren’t 1000 eyes better than two? We probably want to minimize surface area the eyes take, while maximizing maybe peripheral vision? Sure let’s go with that. There’s a left and right side of us, so why not two symmetrical eyes laid across the top part of the face.
Viola! This worm is probably going to survive in the wild seas. Of course we a sadistic goddess so we’ll throw some predators and other obstacles here and there to evolve our little worm. In the process of overcoming hardships, maybe it develops:
1) a nose for higher efficiency of finding food (especially for it’s land based offspring)
2) ears for similar reasons as well as making up for the limitation of the eyes in predatory alerts
3) limbs/fins for more efficient mobilization for hunting/escaping. Maybe a tale for added balance
This thought experiment was to illustrate why we have some of the basic body parts where they are. It’s admittedly over-simplified (I’m no where near being a biologist). The two-eye reasoning could be the reason we have two of other things. Selection seems to favor symmetry along the spine for vertebrates. Some exceptions include:
1) The Wrybill’s Beak
2) The Wonky-eyed Jewel Squid who’s left eye is huge compared to the right. It swims in a 45° angle with the larger eye looking up for prey and the lesser eye looking out for predators. This ‘abomination’ was probably a product of the neighbor pretender-god of evolution, Dinkleberg. Stay away, forever unclean!