Russian Clubtail

The Russian clubtail's tails evolved two marble sized blobs of cartilage-like flesh on their ends of their four tentacle-tails. Alone, the clubtail is still useless. But when attacking in a swarm, they can bring down the biggest predators. This is only defensive however, and the corpse usually sinks to the river floor for scavengers to pick at. The fact the clubtails now had some offense meant they could move closer to the seafloor, where there was more food. Since the water was much richer down lower, there was less of a need for photosynthesis. It still photosynthesises, but only when necessary as it gains enough energy from the microrganisms usually. Also, as another lesser evolution, their eye moved forward to make it easier to target effectively. The Russian clubtail split from the Russian swarmer.