Do Shrimp Bleed? A Closer Look at Shrimp Anatomy and the Red Liquid
As a seafood lover I’ve always wondered if shrimp actually bleed when they are cooked. That red or pinkish liquid that comes out looks like blood, but is it really? In this article, we’ll take a deeper dive into shrimp anatomy to find out if shrimp have blood and what is causing that red ooze when you cook them.
Shrimp Are Crustaceans, Not Fish
First it’s important to understand that shrimp are not fish. They are crustaceans related to lobsters and crabs. This means anatomically, they are quite different from fish.
Shrimp have an exoskeleton made of chitin instead of scales. Their body is divided into two main parts – the head/thorax (cephalothorax) and abdomen. The head houses sensory organs like eyes and antennae, while the abdomen contains muscles that enable swimming.
On the outside, shrimp have swimmerets for mobility, stalked eyes that protrude on eyestalks, and five pairs of legs including front claws used for defense and feeding. Internally, they have a simple heart, a digestive system, gills for breathing, and a nervous system.
Shrimp Don’t Have Blood, They Have Hemolymph
Unlike vertebrates like fish, shrimp don’t have blood. Instead, they have hemolymph flowing through their veins. Hemolymph is composed of water, salts, proteins and other dissolved nutrients.
The main protein hemocyanin binds with oxygen and transports it throughout the shrimp’s body, similar to hemoglobin in human blood. Hemolymph also carries hormones, enzymes, and nutrients to shrimp cells and organs.
While hemolymph can clot to prevent fluid loss after injury, it does not contain red blood cells like human blood. Hemolymph is usually clear or bluish in color.
The Anatomy Behind That Red Liquid
So if shrimp don’t have blood, where does that red ooze come from when you cook them? There are a few sources that contribute to this effect:
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Astaxanthin: This carotenoid pigment provides the pinkish-reddish color in shrimp flesh, lobster shells, salmon, and red algae. When subjected to heat, it leaches out and dyes the liquid.
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Hepatopancreas: This organ in shrimp has a reddish hue and sometimes ruptures during cooking, releasing red/orange fluids.
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Coagulated proteins: Heated proteins from shrimp muscle tissues and organs can coagulate into red globs.
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Hemolymph: Though clear in color, the hemolymph contains coagulable proteins that can turn reddish when subjected to heat.
Other Myths About Shrimp Blood
Let’s bust a couple other misconceptions about shrimp blood and anatomy:
Myth: Shrimp blood is blue.
Fact: As mentioned earlier, shrimp hemolymph is clear or bluish in color, not vivid blue. Only the hemocyanin protein turns blue when exposed to oxygen outside the body.
Myth: Mosquitos can’t bite shrimp.
Fact: Mosquito larvae live in water and can puncture a shrimp’s shell to feed on the nutritious fluids and organic matter inside. But adult mosquitos don’t actually bite shrimp.
Myth: Shrimp membranes are veins filled with blood.
Fact: Shrimp have an open circulatory system so the hemolymph flows freely rather than through veins and arteries. The reddish parts often thought to be blood vessels are actually muscle tissue or organs.
Why Does Hemolymph Turn Red When Exposed to Oxygen?
You may notice that when a shrimp shell is cracked, the hemolymph leaks out clear initially but turns red after contact with air. This is due to oxidation of the hemocyanin protein which changes from colorless to red.
Hemocyanin contains copper atoms that bind oxygen molecules. This is similar to iron in hemoglobin, but copper gives hemolymph a redder hue compared to blood’s dark red color when oxidized.
This color change can be an indicator of freshness – healthier shrimp with fresher hemolymph will turn more reddish. Older stale shrimp hemolymph is paler when oxidized.
Unique Features of the Shrimp Circulatory System
Let’s take a quick look at some of the unique features of a shrimp’s open circulatory system:
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Dorsal heart: A long tube-like heart that pumps hemolymph from end to end.
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Arteries: Distribute hemolymph from heart to body tissues.
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Open spaces: Hemolymph flows freely instead of in enclosed vessels.
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Ostia: Small pores that allow hemolymph to re-enter heart.
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Respiration: Gills and antennae provide oxygen.
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Lower blood pressure: Hemolymph flows more slowly than blood in vertebrates.
While less advanced than our closed circulatory system, this setup efficiently distributes hemolymph within a shrimp’s body cavity.
Conclusion
While shrimp don’t technically have blood, the reddish ooze we see when cooking them certainly looks like blood. Through this article, I hoped to clarify the anatomy behind that red liquid and bust some common myths about shrimp blood.
Understanding their circulatory system provides a deeper appreciation for how well crustaceans like shrimp are adapted to life underwater. So next time you enjoy succulent shrimp, you can dig in with new insight into their physiology. Just don’t forget the cocktail sauce!
Water quality and its effect on hemocyte production
As we will see below, the physical and chemical properties of water, like temperature, oxygen, pH, and salinity, have a lot to do with how many hemocytes are made in response to disease.
Shrimp immune response at different pH levels
Studies conducted with L. vannamei shrimp exposed to a pathogenic strain of Vibrio alginolyticus (8. 0 x 105CFU) at different pH levels showed differences in final survival (Li and Chen 2008). The lowest survivals were obtained at the lowest (6. 5) and highest (10. 1) pH, while the highest survival was obtained at pH 8. 2. However, as the hours of exposure went on, the pathogenic bacteria continued to make it harder to survive in all pH conditions (Fig. 6).
Li and Chen’s (2008) study on how pH affects shrimp survival showed that the concentration of dissolved oxygen is the most important thing to keep shrimp from getting vibriosis. But if the pH changes quickly, shrimp might not be able to survive because their defenses, like phagocytic activity, may not work as well (Fig. 6), even with high concentrations of dissolved oxygen.
10 Most Common Reasons Why Shrimp Die!
Do shrimp have blood?
While shrimp have a circulatory system that serves a similar purpose to blood in transporting nutrients and oxygen throughout their body, their fluid is called hemolymph. Unlike human blood, it does not contain red blood cells or hemoglobin. Additionally, hemolymph does not have a set color and can vary depending on a shrimp’s diet and environment.
What are the side effects of eating shrimp?
Shrimp allergy can be identified from signs and symptoms that appear after consuming shrimp or smelling it, such as itching, the appearance of red plaques on the skin, swelling in the face, especially in the eyes and mouth, and in the throat creating the feeling of a lump in the throat.
Can you eat shrimp steamed?
Shrimp has less than a tenth of a gram of saturated fat in 3 ounces. Plus, there’s almost no trans fat in shrimp. The healthy fats in shrimp, like omega-3 fatty acids, can lower your blood pressure and odds of getting heart disease and stroke. You can eat shrimp steamed, boiled, barbecued, fried, sautéed, poached, or baked.
Is shrimp bad for You?
Shrimp is a great option to lower unhealthy fats in your diet. You’ll cut over 90% of saturated fats if you choose shrimp over the same amounts of steak or cheese. Shrimp has less than a tenth of a gram of saturated fat in 3 ounces. Plus, there’s almost no trans fat in shrimp.