Bug Identifier
Freshwater Hydra
Community identification

Freshwater Hydra

Hydra sp. (likely Hydra vulgaris or similar)

Order & Family
Order Anthoathecata, Family Hydridae
Size
Very small; typically 5mm to 10mm (0.2 to 0.4 inches) when fully extended, but can contract into a tiny blob.
See this bug in the Encyclopedia

Natural Habitat

Found in unpolluted freshwater environments including ponds, lakes, swamps, and aquariums. They typically attach to submerged rocks, plants, or aquarium walls.

Diet & Feeding

Carnivorous predator; feeds on small aquatic invertebrates like daphnia, cyclops, and newly hatched insect larvae or small fish fry using stinging tentacles.

Behavior Patterns

Characterized by its tubular body and ring of tentacles. It is sessile (attached) most of the time but can move by looping (somersaulting) or floating. It has impressive regenerative capabilities and reproduces asexually by budding or sexually.

Risks & Benefits

Generally harmless to humans (too small to sting effectively). However, they are considered pests in aquariums as they can kill shrimp fry and very small fish. They are beneficial in nature as a part of the microscopic food web.