The confusion over whether an anemone is a plant or an animal stems from a shared name referring to two entirely different organisms. The term “anemone” most often describes the colorful, tentacled creature found on coral reefs, which is an animal. However, the name is also used for the delicate terrestrial flowering plant known as the windflower. One is a marine invertebrate belonging to the Kingdom Animalia, while the other is a true flowering plant in the Kingdom Plantae.
The Sea Anemone An Animal
The sea anemone is classified within the Kingdom Animalia and belongs to the Phylum Cnidaria, alongside relatives like jellyfish and corals. It exists primarily as a solitary polyp. The sea anemone’s structure is a cylindrical body, often attached to a substrate by an adhesive pedal disc, topped by an oral disc surrounded by tentacles.
These tentacles are armed with specialized stinging cells called nematocysts, which capture and paralyze passing prey such as small fish and plankton. The nematocysts fire a microscopic, harpoon-like filament containing neurotoxin upon contact, a defining characteristic of Cnidarians. Although often fixed in one place, they possess the ability to detach and move slowly by creeping or, in some species, by a somersaulting motion.
The anemone has a simple nervous system composed of a nerve net, allowing it to process basic stimuli like touch and chemical changes to react to its environment and prey. Its digestive system is a simple gastrovascular cavity with a single opening functioning as both mouth and anus. In many species, the anemone supplements its diet through a symbiotic relationship with zooxanthellae, single-celled algae that perform photosynthesis within its tissues.
The Windflower A True Plant
The organism known as the windflower is a plant, categorized in the genus Anemone and belonging to the buttercup family, Ranunculaceae. This herbaceous perennial is a terrestrial flowering plant native to temperate and subtropical regions globally. The common name “windflower” is derived from the Greek word anemos, meaning “wind,” reflecting how the delicate petals sway in the breeze.
Structurally, the windflower includes a root system, stems, and leaves. It grows from tubers or rhizomes, with basal leaves that are often lobed or toothed. The showy, cup-shaped flowers are borne on slender stalks and feature petal-like sepals, ranging in color from white and pink to blue and purple.
The windflower relies on photosynthesis, a biochemical process that converts light energy into chemical energy to create its own food. This process takes place within the leaves and other green parts. The life cycle involves producing seeds, which are often contained in achenes dispersed by the wind.
Key Differences in Function and Structure
The fundamental difference between the two organisms lies in their method of obtaining energy, which dictates their classification. The sea anemone is a heterotroph, meaning it must consume other organisms for nourishment, primarily through predation using its stinging cells. In contrast, the windflower is an autotroph, capable of producing its own food through photosynthesis.
Another distinction is found in their cellular composition and resulting motility. Plant cells, including those in the windflower, are encased in rigid cell walls made of cellulose, which provides structural support and results in a fixed, rooted existence. Animal cells, such as those in the sea anemone, lack these rigid cell walls, having only a flexible cell membrane.
This lack of a rigid cell wall allows the sea anemone, despite its mostly sedentary nature, to exhibit limited movement, change its shape, and actively engulf prey. The windflower, anchored by its roots, is completely non-motile. These differences in nutrition, mobility, and basic cellular structure confirm the sea anemone is an animal and the windflower is a plant.