The adult blue crab’s circulatory system, Callinectes sapidus, was mapped by either injecting barium sulfate into whole animals and then taking x-rays or using resin corrosion casts (Batsons Monomer). Seven arteries arise from the heart. When the anterior aorta leaves the front dorsal surface of the heart, it gives rise to the optic arteries. These arteries bring blood to the supraesophageal ganglion and eyestalks. Paired anterolateral arteries also leave the front dorsal surface of the heart and bring blood to the gonads, hepatopancreas, stomach, antennal gland, mandibular muscles, and the hypodermis of the front of the thorax brain. The paired hepatic arteries exit the heart anteriorly and ventrally and branch profusely within the hepatopancreas. A smaller side branch, the pyloric hepatic artery, supplies hemolymph to the pyloric stomach and midgut. The smallest artery, the posterior aorta, branches off from the back ventral surface of the heart. It meets the inferior abdominal artery near the second abdominal segment, and these two arteries bring blood to the back and abdomen. The largest artery is the sternal artery, which comes out of the heart’s ventral surface. The ventral thoracic artery branches off from the sternal artery and brings blood to the chelae, mouthparts, and each pereiopod. The current research shows that the circulatory system is very well developed, with arteries splitting into smaller capillary-like vessels that connect to many other organs. The return vessels, the sinuses, are discrete channels rather than random open spaces, as previously described. This study adds to and improves previous descriptions of the circulatory system. It is also talked about in relation to new research on hemolymph flow in crustaceans.
With their hard shells, scuttling legs, and savage claws, crabs seem more machine than animal Yet beneath that tough exterior, crabs have complex internal anatomy enabling their survival. A key organ is the heart, pumping life-sustaining hemolymph throughout the crab’s body But do all crabs actually have hearts? Let’s crack through the shell covering and explore the cardiovascular systems of these amazing crustaceans.
An Overview of Crab Anatomy
Crabs belong to the subphylum Crustacea and the order Decapoda, meaning “ten feet.” True to their name, crabs have five pairs of legs for walking, swimming, feeding, and self-defense. Other key body parts include:
-
Carapace – The hard upper shell covering the cephalothorax (fused head and thorax).
-
Abdomen – The tail section where digestion and reproduction occurs.
-
Antennae – Sensory organs that detect chemicals and vibration
-
Eyes – Crabs have compound eyes on movable stalks.
-
Mouth – Consists of mandibles and maxillae for manipulating food
-
Gills – Located under the carapace for extracting oxygen from water.
Now let’s look inside at crab circulation.
The Crustacean Circulatory System
Unlike vertebrates, crabs and other crustaceans have an open circulatory system where blood flows freely within cavities and channels. There are no capillaries or veins.
Oxygenated blood is pumped by the heart through arteries branching into smaller vessels. Hemolymph bathes tissues and organs before draining into spaces called sinuses and lacunae. It then flows back to the gills for re-oxygenation.
This open system is efficient for distributing nutrients and oxygen. And with blood contained, crabs can survive losing a limb.
Do All Crabs Have a Heart?
The vast majority of crab species do have a heart, enabling circulation of hemolymph. According to research on blue crabs and other crustaceans, the heart is located dorsally in the cephalothorax region.
There are a few exceptions where crabs lack a distinct heart:
-
Spider or king crabs have a long body and distribute hemolymph via vessel contractions.
-
Smaller pea crabs rely on muscle movement for circulation.
-
Larval crab stages may not have a developed heart.
For most adult crabs, however, an anatomical heart powers circulation. In blue crabs, the heart is a semi-circular structure wrapped around the single dorsal artery.
How Does a Crab Heart Work?
The crab heart is neurogenic, meaning it pumps through nervous stimulation rather than autorhythmic muscle contractions as in vertebrates.
There are three main phases in crab heart function:
-
Cardiac ganglion neurons stimulate heart muscle cells to contract.
-
Heart contraction squeezes blood into arteries. One-way valves prevent backflow.
-
Heart relaxes, filling again from hemolymph in surrounding sinuses.
This synchronized activity circulates hemolymph to exchange gases, nutrients, and waste. The system maintains blood pressure to operate the gills, deliver oxygen, and remove carbon dioxide.
Unique Features of Crab Cardiovascular Function
Beyond the differences from vertebrate circulatory systems, crabs have other fascinating adaptations:
-
As arthropods, oxygen is delivered directly by the blood rather than transported by hemoglobin.
-
The sternal artery regulates hemolymph flow to the gills for oxygenation.
-
Hemocyanin protein in the blood enhances oxygen transport. This is blue when oxygenated.
-
Crab blood contains important hormones and coagulants for wound healing.
-
Changes in temperature, salinity, and exercise alter heart rate. This adapts flow rates to the crab’s needs.
Caring for a Crab’s Cardiovascular Health
For crabs in captivity as pets or laboratory animals, consider these tips for maintaining heart health:
-
House crabs appropriately – proper habitat size, hides, moisture and pool access. Reduce stress.
-
Feed a nutritious diet including omega fatty acids for heart health. Appropriate veggies, algae, calcium sources.
-
Maintain good water quality – appropriate salinity, pH, temperature and filtration.
-
Avoid heavy metals and toxins that could damage heart tissues.
-
Support molting for growth – provide hideaways and moisture.
-
Stimulate exercise – opportunities to walk naturally and explore.
-
Perform regular exams and health checks at molts. Seek veterinary care for any abnormalities.
Add to My Bibliography
- My Bibliography
Unable to load your delegates due to an error
Save citation to file Format:
- Create a new collection
- Add to an existing collection
Name your collection: Name must be less than 100 characters Choose a collection: Unable to load your collection due to an error
6. Insect circulatory system
Do crabs have a heart?
Like all animals, crabs have a heart that pumps blood throughout their body. However, unlike most animals, a crab’s heart is located in its back and pumps blood through open vessels. In addition to their gills, crabs also have a pair of lungs that allow them to breathe air when they are out of the water.
Are coconut crabs healthy to eat?
Crabs are rich in omega 3 fatty acids, protein, vitamins like riboflavin and minerals like selenium, copper, phosphorus. Coconut crabs are not known to be poisonous. The fat in the abdomen and the egg inside the female are the delicious edible parts. It is prepared by steaming or boiling them in coconut milk. Consuming coconut crab along with sea mango, cerbera manghas may make the coconut crab toxic due to the presence of cardiac cardenolides(cardiac active steroids). This causes electrolyte imbalance that affects the electrical conductivity of the heart.
Do crabs have a circulatory system?
Without further ado. Let’s look at each of these organs and systems in detail. As with all crustaceans, crabs have an open circulatory system. It means that all their blood (Hemolymph) is not only contained within veins and arteries.
Do crabs have a brain?
In crabs, the brain consists of 3 pairs of ganglia: the tritocerebrum (Integrates sensory information from protocerebrum and deutocerebrum). Note: Crabs do not have a brain like that of mammals. Instead, nerve cells concentrated in a set of ganglia. The ganglia interconnect by bundles of nerve fibers that transport the signals at high speed.