Shrimp are aquatic crustaceans entirely dependent on water for survival; they cannot breathe air. Their physiological design is specialized for an underwater existence, relying on an efficient system to draw oxygen suspended within the water itself. Unlike terrestrial animals, shrimp are unable to use the oxygen in the Earth’s atmosphere.
How Shrimp Extract Oxygen From Water
Shrimp acquire oxygen through gas exchange across their delicate gill membranes. They use gills to extract dissolved oxygen (DO) from the surrounding water via the passive process of diffusion. This mechanism relies on a concentration gradient, moving oxygen naturally from the higher concentration in the water to the lower concentration in the shrimp’s blood.
The water flowing over the gills carries dissolved oxygen, which passes across the thin, vascularized surfaces into the shrimp’s hemolymph (blood). Simultaneously, carbon dioxide diffuses out of the hemolymph into the water to be carried away. This continuous transfer requires the gills to remain submerged with water constantly moving across them.
Anatomy of the Respiratory System
A shrimp’s respiratory organs are located within a protected space on either side of its body, called the branchial chamber. This chamber sits beneath the carapace, the hard shell covering the shrimp’s cephalothorax (head and thorax). The gills are delicate, feather-like structures stacked in rows, often resembling the pages of a book due to their numerous thin plates.
The respiratory system requires the active creation of a constant water current over the gills. This movement is generated by a specialized appendage called the scaphognathite, or “gill bailer,” which is part of the second maxilla. The scaphognathite acts like a paddle, beating rhythmically to draw water into the posterior and ventral openings of the branchial chamber. This action ensures a unidirectional flow of fresh, oxygenated water across the gill filaments before it is expelled from the anterior end.
Survival When Exposed to Air
The aquatic specialization of the shrimp’s respiratory system explains why they cannot survive long when exposed to air. The delicate, moist gills are designed to be supported by water; when submerged, the thin gill filaments are held apart, maximizing the surface area for gas exchange.
When removed from water, the lack of buoyant support causes these fine gill filaments to collapse and stick together. This physical collapse drastically reduces the surface area for oxygen absorption, causing the shrimp to quickly suffer asphyxiation. Air cannot be processed because the respiratory membranes must remain wet for diffusion to occur effectively.
The shrimp also faces rapid desiccation (drying out). Gills are highly permeable for gas exchange, meaning they lose moisture quickly in a terrestrial environment. The combination of structural collapse and accelerated water loss means most shrimp species can only survive for a few minutes outside of water.