Compare And Contrast Octopus And Moon Jellyfish

The following analysis is a comparison of two marine animals, octopus, Octopoda, and the moon jelly, Aurelia aurita, and how their nervous systems differentiate. Octopus have bilateral symmetry and jellyfish have radial symmetry which correlates to their body functions. Both species behave differently but share similar features, although they are not related and have unique developments which evolve over time.

The two species to be compared are the octopus, Octopoda, and the moon jelly, Aurelia aurita. Octopus and moon jellies are found in various parts of the ocean and usually stay near shallow water where coral reefs are. Octopus, however, can go deeper in the ocean down to 500 feet (New England Aquarium 2023). Octopus and jellyfish both

Cephalopods contain chromatophores which are pigment sacs that change color to match their surroundings. They are the only phylum to possess an active image generating neuromuscular system (Hochner, 2004). They are perfect for camouflage against predators since they are soft-bodied and vulnerable to other mammals. There are 5 different sacs of chromatophores including black, brown, orange, yellow, and red (Hochner, 2004). Octopus contain 8 arms covered with suction cups that stick onto other objects. They have an antagonistic muscle system in which the constant volume constraint causes the muscles to act against each other, defines these structures as muscular hydrostats (Hochner, 2004). Their flexibility and muscles give them an advantage to hide in small spaces or capture prey. Their giant axon system is what makes them act fast by swimming rapidly with jet propulsion. This is what makes them able to escape and emit ink which is among all cephalopods. The ink they emit is to distract predators when they are close by, giving the octopus a chance to escape. Octopus have human-like eyes with sensory cells which resemble convergent evolution. This gives them exceptional eyesight to know what is around them. An organ called a statocyst gives them balance and orientation which also resembles convergent evolution (Hochner, 2004). Their brain also causes them to possess unique behaviors

The nerve net is more complex than one might think since these jellyfish have receptors that respond to light, touch, gravity, chemicals, sound pressure waves, direction, vibration, and hydrostatic pressure (Albert, 2011). Although they seem to only float in water, they rely on reflexes to survive. Jellyfish have been able to evolve for 500 million years which proves they are significant in our oceans. Moon jellies particularly are the most common and well-known phylum of Cnidaria. Their central nervous system is a group of nerve nets structured in various ways, containing several receptors. They have light receptors called ocelli that help guide them and gravity sensors called statocysts that help maintain their balance just like octopus. A unique trait about Cnidarians is their nematocysts that sting prey and inject them with toxins (Albert, 2011). Moon jellies are also sensitive to light which is caused by their photoreceptors. This is why these species are typically seen during the day near the shore. Jellyfish are responsive to touch from mechanoreceptors and can detect chemical scents from other animals by chemoreceptors. Stimulation from their cilia can also help them sense gravity. They can detect sound pressure and vibration due to their ciliary hairs in the statocysts. It’s thought they have directional sensor from sunlight, but