Megaorthoceros Segnoneustes

Another of Sagan 4's fantastic creatures, the Megaorthoceros segnoneustes exhibits extreme sexual dimorphism, with the females quite easily having the longest proboscis on the planet, with it measuring many times the length of the body itself.

They swim by using a long, thickened flagellum that now operates more like a sturdy tail, and control their movement from side to side with a pair of long fin-like extensions; the length of these help to turn it faster, as it has more surface area to push against water, to counteract to an extent the amount of water pushing against the proboscis.

This long proboscis in females is a multi-purpose tool, and is used as not only the feeding implement, but also a reproductive organelle and sensory organelle.

Females of the species are detrivorous, and use their proboscises to first "sniff out" dead organisms by sensing particles. Once they find the dead organism, they stick the tip of their proboscis in and suck out the rotting juices. Here, the length helps to keep them further from their meal, making them less likely to get eaten accidentally by some of the opportunists that may appear.

Males on the other hand are very small; so small in fact they only need to be chemovores, digesting only the chemicals they require to stay alive long enough to find a mate.

The Megaorthoceros segnoneustes breed through sexual budding. This is caused when a male, who is far smaller than the female, is sucked in through her enlarged proboscis; from here it takes on a symbiotic lifestyle, and become permanently bonded with her on the inside, where he will use nutrients gathered from her to survive, all the while fertilizing her for the budding process. This budding is little more than a highly-specialized form of mitosis.

Once fertilized, the female then begins to gain two bulbous growths that flank her tail, which grow into nearly full-sized females. Although these are essentially temporary, they can help balance the weight of the proboscis, allowing females carrying nearly-"matured" megaorthocerosi to fully counter-balance the proboscis and swim quite well. However, once the buds split off, the females must return to a low-swimming life on the seabed, until the next two buds have begun.

These buds possess a fully-developed body, but have smaller fins, tails, and proboscises, which must grow to full-size over time. This is to prevent the original female from killing herself by using too much of her own nutrients to create the two new females.

Males are created by females after they have reached about half their final size, and are "spit" out in a cloud by the female. Since half-grown females won't breed, these males cannot just turn around and fertilize her on the spot, and must seek other females instead.

Because of their powerful smelling organelles lining their proboscis, their nucleus has grown to a significant size.

They can be found in both freshwater and marine environments, so long as the waters are tropical.