Snails possess a circulatory fluid, often called “blood,” which can leak from their bodies when injured, indicating a form of bleeding. This fluid circulates throughout their bodies, performing functions similar to blood, but with distinct characteristics.
The Unique ‘Blood’ of Snails
The circulatory fluid in most snails is called hemolymph, a substance that combines the roles of blood and lymph found in more complex circulatory systems. This hemolymph is typically bluish in color, a distinctive hue that comes from a copper-containing protein known as hemocyanin. Hemocyanin is responsible for transporting oxygen throughout the snail’s body, analogous to how hemoglobin carries oxygen in red-blooded animals. When hemocyanin binds with oxygen, it appears blue; without oxygen, it becomes colorless or pale yellow.
Hemolymph is a complex mixture, comprising water, various inorganic salts (such as sodium, chloride, potassium, magnesium, and calcium), and organic compounds (like carbohydrates, proteins, and lipids). This composition allows it to carry nutrients, hormones, and waste products, supporting the snail’s metabolic functions. While most snails utilize hemocyanin, some species, like the Common Ramshorn Snail, have red hemolymph due to hemoglobin.
How Snails Circulate Their Fluid
Snails employ an open circulatory system where hemolymph is not entirely confined within blood vessels. A two-chambered heart pumps hemolymph through short arteries into open spaces or sinuses within the body cavity.
In these sinuses, hemolymph directly bathes organs and tissues, delivering oxygen and nutrients. This direct contact allows for effective exchange of substances between the fluid and cells. After circulating through these open spaces, deoxygenated hemolymph collects and flows back towards the heart for re-oxygenation and recirculation. This system, less pressurized than the closed circulatory systems of mammals, suits the snail’s relatively low metabolic needs.
What Happens When a Snail is Injured?
When a snail is injured, its hemolymph can leak, appearing as a clear to light blue fluid. Despite this, snails demonstrate a notable capacity for recovery from various injuries, particularly to their shells.
For minor shell damage like cracks or chips, snails can repair themselves by secreting new calcium carbonate to mend the break. This shell regeneration can take weeks to months, depending on the damage severity.
For body tissue damage, the snail’s hemolymph contains components that aid wound healing, including substances that influence blood clotting. Research suggests hemolymph acts as a hemostatic agent, helping to stop external bleeding. The snail’s resilience and ability to regenerate tissue, combined with these clotting mechanisms, contribute to its survival after injury.