Cnidarian
16 cnidarian organisms and their business parallels
Box Jellyfish
The box jellyfish is the immortal jellyfish's opposite: rather than achieving longevity through lifecycle reversal, it invests in being the most venom...
Budding Hydra
Hydras reproduce primarily through budding—a small copy of the parent grows directly from the body wall, then detaches as an independent organism. The...
Colonial Hydroid
Obelia is a colonial hydroid—essentially a branching colony of hydra-like polyps connected by living tissue. Each polyp can regenerate, and the colony...
Coral
Individual brain coral colonies can live over 500 years, which means some corals alive today began growing before the founding of the United States. T...
Coral Polyps
Coral polyps are tiny animals that secrete calcium carbonate skeletons. Over time, these skeletons accumulate into coral reefs - the most diverse mari...
Coral-Zooxanthellae System
Coral reefs are built on mutualism. The coral animal provides shelter and CO2; symbiotic algae (zooxanthellae) living in coral tissues provide up to 9...
Fire Coral
Fire corals aren't true corals - they're hydrozoans more closely related to jellyfish. But they build calcium carbonate structures indistinguishable f...
Freshwater Polyp
Hydra oligactis is a close relative of the 'immortal' Hydra vulgaris, but with a crucial difference: it ages. While H. vulgaris shows no senescence an...
Green Hydra
Green hydra carry photosynthetic algae (Chlorella) within their cells, creating a self-feeding system. The hydra provides protection and nutrients; th...
Moon Jellyfish
Moon jellyfish have a complex lifecycle alternating between polyp and medusa (jellyfish) stages. The swimming medusa is the visible form, but the poly...
Portuguese Man o' War
The Portuguese man o' war appears to be a single jellyfish but is actually a colony of four types of specialized organisms (zooids) that cannot surviv...
Sea Anemone
Sea anemones provide clownfish protection from predators through their defensive arsenal of stinging tentacles - few species dare approach. In return,...
Sea Anemone
Sea anemones share the hydra's basic body plan—a tube-shaped body with tentacles surrounding a mouth—and appear to share its potential for biological...
Sea Fan
Sea fans are gorgonian corals that build flexible, fan-shaped colonies rather than rigid limestone structures. They orient perpendicular to currents,...
Siphonophore
Giant siphonophores can reach 150 feet - potentially the longest animals on Earth - yet like man o' war they're colonial organisms. Thousands of speci...
Staghorn Coral
Staghorn coral grows up to 8 inches per year - extraordinarily fast for a reef-building coral. Its branching structure creates three-dimensional habit...