Hydra (freshwater organism) capturing a water flea (Daphnia) 插畫檔

Hydra (a small, freshwater organism) capturing a water flea (specifically a Daphnia.1. The Predator: HydraThe Hydra is a member of the phylum Cnidaria, making it a close relative of jellyfish and sea anemones.Tentacles: It uses these long, flowing arms to "fish" for food in the water.Stinging Cells (Cnidocytes): The tentacles are covered in specialized cells called cnidocytes. When a water flea brushes against them, these cells explode, launching microscopic venomous harpoons (nematocysts) that paralyze the prey.Regeneration: Hydra are famous in biology for being "immortal"—they do not appear to age and can regrow their entire body from just a few cells.2. The Prey: Water Flea (Daphnia)Despite the name, a water flea is not an insect; it is a tiny crustacean.Movement: They use their large, branched antennae (the "arms" seen at the top of the flea in the drawing) to jump through the water in a jerky motion.Diet: While the Hydra eats them, the Daphnia itself is a filter feeder, eating even smaller algae and bacteria.