Crabs are a type of crustacean, consisting of short-tailed marine creatures with shells and large claws that can be found worldwide.
A crab’s initial form is a larva or zoea. This growth process transforms it from a tiny creature into something larger before its shell hardens.
Fish
Crabs are omnivorous animals, meaning they feed on both plants and fish. Common food sources for crabs include algae, water plants, small fish, other crabs, shellfish, and occasionally dead fish or decaying vegetation.
Crabs use their powerful pincers and claws to quickly locate food sources. These tools include two pairs of specialized claws that enable them to crush or break through shells on various sea life, as well as chop and pick the food into smaller pieces so it is easier for them to consume.
Blue crabs are an integral part of the Chesapeake Bay ecosystem, feeding on various small animals to maintain their populations. Primarily feeding on clams, blue crabs also feed on other invertebrates like snails and shrimp for sustenance.
Clams are a staple diet for blue crabs, as they contain high amounts of nutrients such as amino acids, fatty acids, protein, and energy. Plus, blue crabs possess the unique ability to crack open clam shells with their sharp teeth in order to access the flesh within.
Blue crabs rely heavily on muscle tissue from recently deceased fish as a source of nutrition. This is because freshly dead muscles are easier to digest for crabs than their fleshy counterparts, allowing them to retain energy and grow rapidly during their brief lives.
Mollusks
Crabs, lobsters, shrimp, crayfish, and other crustaceans belong to the taxon Crustacea. These omnivorous creatures feed on a variety of foods; some crabs tend to be scavengers while others are predators that hunt and consume other crustaceans.
Sand crabs feed on microscopic plankton, mollusks, and algae found in the sand. As tides come in and out, they move along the beach in search of food as they search for new prey.
Horseshoe crabs possess an organ called the rostrum, which allows them to physically reach the soft body inside of shelled animals such as clams, oysters, and mussels. With pressure from their mandibles and claws, they can open these animals’ shells and even pry them apart.
Bivalves are not true filter feeders, but they can still contribute to water purification by pumping it through their gills and capturing microscopic particles. Furthermore, these mollusks recycle nutrients back into the sea by feeding on plankton that has been filtered from the sea by other mollusks or marine life through similar mechanisms.
Crabs, such as blue and horseshoe crabs, typically feed on snails, clams, and other mollusks due to their abundance in their natural habitat. Mollusks provide them with easy access to nutrition while being highly sought-after by crabs.
They’re an excellent source of calcium, protein, and vitamins. Unfortunately, shellfish can become foodborne illness if not cooked or stored properly – so be sure to steer clear of raw or improperly prepared shellfish.
Birds
Crabs are land-dwelling creatures with two large eyes on movable stalks, antennae on their heads, and mouths on the underside of their heads. They feed on both dead and living animals alike.
Crabs often feed on birds, taking meat from their bodies – which may consist of bones and flesh. They may use their teeth to tear into the bird’s skin for added enjoyment.
Researchers in the Chagos Archipelago have captured a rare video of a coconut crab stalking and killing an adult seabird on an island in the Indian Ocean. This is the first time scientists have witnessed these massive crustaceans taking on such large prey items.
These enormous crabs, which can grow to over one meter (three feet) long and weigh as much as nine pounds, are a feared predator on coral atolls in the tropical Indian and Pacific oceans. With legs that span up to one meter across, these invertebrates are the largest without backbones.
They are renowned for their sapphire blue claws, which they use to crack open coconuts. These reptiles have been found living on many islands around the world, from Africa to the Gambier Islands of the Eastern Pacific.
Coconut crabs not only feed on birds but other sea creatures as well. Reports have surfaced of them eating oysters, clams, insects, mussels, and worms.
At high tides, they often swim into salt marshes to search for snails and other prey. They have also been known to catch prey between their claws when something swims past them or walks past.
Predators
Crabs are opportunistic predators and scavengers, meaning their diet can be quite varied. They feed on algae, plant matter, animal detritus, and even some dead animals when kept in captivity. When offered food items such as fish, fruits, vegetables, breads, cookies, insects, or shells they will consume whatever is provided to them – even fish!
Crabs in the sea possess four pairs of legs and powerful claws which they use to hunt their prey. They use these limbs for manipulating food, defending themselves from other crabs, and courting potential partners.
Some crabs, like the horseshoe crab, molt their exoskeleton several times to grow larger. Unfortunately, this process leaves them more vulnerable and makes them easier for larger predators to capture.
Other crabs rely on their strong shells to protect them from predators. Unfortunately, smaller crabs may be more vulnerable due to having fewer limbs than larger crabs and being unable to completely encase themselves in shells.
Crabs can become easily caught by small fish and crab-eating shorebirds. Additionally, these predators will eat crabs that get stuck on the shore or in tide pools during low tide.
Blue crab shells are tough and can withstand long periods of immersion in the ocean, but they have a limited lifespan. Blue crabs usually succumb to being consumed by an adult fish that is much bigger than them – usually an adult shark or seal.
Researchers have discovered that blue crabs can identify and track their prey using vision and touch. Furthermore, their chemical receptors detect scents from prey based on the water flow around them.