Shrimp are decapod crustaceans that inhabit oceans and freshwaters around the world, enjoyed by humans as a popular seafood. But do these small, aquatic creatures have hearts?
If you’re short on time, here’s a quick answer to your question: Yes, shrimp do have hearts. Their cardiovascular system includes a heart and arteries that pump hemolymph fluid through their bodies.
In this approximately 3000 word article, we’ll take an in-depth look at shrimp anatomy, examining the structure and function of their circulatory system and heart. We’ll compare shrimp anatomy to other crustaceans and animals. And we’ll answer some common questions about shrimp hearts and biology.
Shrimp Anatomy and Circulatory System
External Anatomy
The external anatomy of a shrimp includes several key features. Shrimps have a hard exoskeleton that protects the internal organs. They also have compound eyes on movable stalks, two pairs of antennae for sensing food and navigation, mouthparts for feeding, appendages called pereiopods for gathering food and locomotion, a muscular abdomen for swimming backward rapidly, and a tail fan for steering.
Internal Anatomy and Hemolymph
Inside their hard exoskeleton, shrimps have a digestive system, circulatory system, nervous system, reproductive system and muscles. Instead of blood, shrimps circulate a fluid called hemolymph to transport nutrients and oxygen.
Hemolymph flows into spaces called sinuses within the body and around the organs, rather than being confined to blood vessels like in vertebrates.
The Shrimp Heart
Yes, shrimps do have a heart, despite their relatively simple circulatory systems. The shrimp heart is a muscular chamber located in the cephalothorax region, just behind the mouthparts. The heart pumps hemolymph through an open circulatory system that directly bathes their organs.
The pumping action moves the hemolymph through the system of sinuses and spaces between organs and muscle tissues. This allows oxygen and nutrients to reach cells efficiently in order to meet their high energy demands.
The shrimp heart has multiple openings where hemolymph enters, called ostia. There are also two exit points where hemolymph is pumped out of the heart into two main arteries for circulation. The heart beats rapidly, contracting up to
So in short, shrimps do have functioning hearts to pump fluid and enable gas exchange, nutrient transport and waste removal, despite lacking advanced cardiovascular systems like those found in vertebrates.
Their efficient open circulatory systems with beating hearts meet the needs of these highly active crustaceans.
Comparing Shrimp Hearts to Other Crustaceans
Crabs
Like shrimp, crabs are decapod crustaceans that belong to the order Decapoda. This means they have 10 legs and an exoskeleton made of chitin. Crabs have a heart known as a dorsally located heart or pericardial sinus located just under the carapace (shell).
The crab heart has a single ventricle and no septum, so oxygenated and deoxygenated blood mix. Their heart beats at about 60-120 beats per minute depending on the species and pumps blood into the hemocoel cavity to bathe tissues. From there, blood seeps back to the gills where gas exchange occurs.
Lobsters
Lobsters are also decapod crustaceans closely related to shrimp anatomically. They too have a dorsally located heart that pumps mixed oxygenated and deoxygenated blood into the hemocoel. Their single ventricle heart beats at about 60 beats per minute.
One difference is lobsters tend to have larger hearts and blood volumes than other decapods. Their hearts span almost the entire length of their body! This likely helps them be more active swimmers than some other decapods.
Crayfish
Crayfish are freshwater crustaceans that belong to the families Astacidae, Cambaridae, and Parastacidae. They are decapods like shrimp, crabs and lobsters. Their heart anatomy and function is quite similar as well.
Crayfish have a dorsally located single ventricle heart located under the carapace that pumps mixed oxygenated and deoxygenated blood into an open circulatory system and hemocoel. Their hearts beat at about 60-120 beats per minute depending on the species.
One unique fact about crayfish is they can actually reverse the direction of heart pumping quickly, which aids in escaping predators.
Shrimp Hearts vs. Fish and Mammal Hearts
Fish Hearts
The anatomy of a shrimp’s heart significantly differs from the hearts of fish and mammals. Fish have a two-chambered heart with one atrium and one ventricle. Oxygenated blood from the gills enters the atrium, then moves to the ventricle which pumps blood to the rest of the body.
The single circuit means deoxygenated blood mixes with oxygenated blood. This simpler circulatory system works for fish living in water where oxygen levels are consistently high.
In contrast, a shrimp’s heart has a single chamber and resembles a tube running along the length of its body. Despite its simple structure, the shrimp heart efficiently circulates hemolymph (circulatory fluid) throughout the body.
The tube-like heart contracts rhythmically, propelling hemolymph through arteries. Hemolymph enters spaces called sinuses which distribute it to tissues before it flows back to the heart through veins.
Mammal Hearts
Mammals, including humans, have more complex four-chambered hearts with two atria and two ventricles. This double-circuit system completely separates oxygenated and deoxygenated blood. Oxygenated blood from the lungs fills the left atrium then moves to the left ventricle which pumps it to the body.
Deoxygenated blood returns from the body to the right atrium, then fills the right ventricle which pumps to the lungs to become re-oxygenated.
This efficient separation allows mammals to meet the high oxygen demands of warm-blooded metabolism. The powerful left ventricle propels oxygenated blood through the vast systemic circulatory system. Meanwhile the weaker right ventricle circulates deoxygenated blood through the pulmonary loop.
In contrast, a shrimp’s simple tube heart and single circuit are sufficient for a cold-blooded invertebrate with less complex circulatory needs.
Frequently Asked Questions About Shrimp Hearts
Do baby shrimp have hearts?
Yes, baby shrimp do have hearts from the very early stages of their development. Once the shrimp embryo forms, one of the first organs to develop is the heart. The embryonic shrimp heart starts beating within the first few days after fertilization.
This primitive tubular heart pumps blood through the developing circulatory system. As the shrimp grows and develops, the heart also matures and becomes more complex. The baby shrimp’s heart is critical for delivering oxygen and nutrients throughout its tiny body.
Without a functioning heart, the shrimp larvae would be unable to survive and grow. So in short – the shrimp heart is vital right from the start!
Do freshwater shrimp have hearts?
Yes, freshwater shrimp have hearts that serve the same essential function as their saltwater cousins. The cardiovascular system of freshwater shrimp consists of a dorsal heart or “cardiac stomach” along with arteries and hemolymph sinuses.
The cardiac stomach is a muscular pump that propels hemolymph (shrimp blood) throughout the body. Freshwater shrimp hearts have one anterior opening through which hemolymph enters, and a pair of lateral openings where hemolymph exits to be circulated through the arteries.
Some key differences are that freshwater shrimp hearts tend to beat slower than marine shrimp hearts, and their hemolymph has lower salt concentrations. But the basic anatomy and purpose is the same – providing oxygen and nutrients to shrimp tissues.
So whether it’s a Neocaridina davidi or Macrobrachium rosenbergii, freshwater shrimp could not survive without their trusty little hearts!
Do shrimp hearts pump blood?
Not exactly. Shrimp hearts pump a fluid called hemolymph rather than blood. Hemolymph performs most of the same vital functions as blood like transporting nutrients and oxygen. However, there are a few key differences:
- Hemolymph doesn’t contain red blood cells or hemoglobin like vertebrate blood.
- Hemolymph flows freely within the body cavity and sinuses rather than closed veins.
- Hemolymph contains far fewer cells overall than blood.
The heart or “cardiac stomach” creates rhythmic contractions to keep hemolymph flowing around the shrimp’s open circulatory system. Hemolymph first enters the heart through an incurrent opening, then gets pumped out side exits called ostia.
From there it circulates through sinuses and arteries before re-entering the heart. While not exactly the same as blood, hemolymph is vital for delivering nutrients absorbed from food to the shrimp’s tissues and organs. The shrimp heart works tirelessly to keep hemolymph pumping!
Conclusion
Shrimp have a simple tubular heart through which hemolymph flows, powering their small but complex circulatory system. Their cardiovascular anatomy allows oxygen and nutrients to reach tissues and organs.
While structurally different from vertebrate hearts, the shrimp heart serves the same crucial role of circulating fluids through the body. Understanding the circulatory system and heart provides insight into the physiology that enables shrimp to thrive in their aquatic environments.
