Classification: Phylum: Arthropoda Subphylum: Chelicerata Order: Xiphosurida

Related To: More closely related to spiders and scorpions than to true crabs.

Habitat: Found along the Atlantic coast of North America, especially in shallow coastal waters and estuaries with sandy or muddy bottoms.

Lifestyle: Scavenger and predator. Eats worms, mollusks, and algae.

Feeds using its legs, which push food toward its mouth located in the center of its body.

Active mostly at night and often comes ashore during spring high tides to mate.

Defensive/Offensive Mechanisms: Hard, dome-shaped carapace protects it from predators.

Has a long, pointed telson (tail) used for flipping itself over if turned upside down, not for stinging.

Unique Structures: Blue blood that contains a substance called Limulus Amebocyte Lysate (LAL), which is used to test for bacterial contamination in medical equipment.

Compound eyes and multiple simple eyes—excellent light sensitivity.

Interesting Facts: Considered a "living fossil"—has existed for over 450 million years.

Plays a vital role in the ecosystem; its eggs are a key food source for migratory birds.

Phylum: Arthropoda

Subphylum: Chelicerata

Order: Xiphosura

Related Animals

Despite their name, horseshoe crabs are not true crabs! They are more closely related to arachnids like spiders and scorpions than to crustaceans.

Habitat

American horseshoe crabs are found along the Atlantic coast of North America and in the Gulf of Mexico. They prefer shallow coastal waters and often migrate to sandy beaches for spawning.

Lifestyle & Diet

They are scavengers, feeding on worms, mollusks, and small invertebrates.

They use their legs to crush food before consuming it.

They do not actively hunt but instead search the ocean floor for food.

Defensive & Offensive Mechanisms

Their hard exoskeleton provides excellent protection against predators.

They have a long, pointed tail (telson), which helps them flip over if they get stuck upside down.

They are not aggressive and rely on their armor rather than offensive tactics.

Unique Structures

Their blue blood contains Limulus amebocyte lysate (LAL), which is used in medical testing to detect bacterial contamination.

They have compound eyes that help them navigate in murky waters.

Interesting Facts

Horseshoe crabs are often called “living fossils” because they have remained virtually unchanged for over 350 million years!

Their eggs are a vital food source for migratory shorebirds.

They play a crucial role in scientific research and medicine due to their unique blood properties.

Classification: Malacostracans

Related to: All other species of krill

Habitat: primarily inhabit the cold, open waters of the Southern Ocean, a region that includes the Southern and Indian Antarctic Oceans, and the Antarctic Peninsula

Lifestyle: daily vertical migrations, reliance on sea ice for survival, and a crucial role in the Southern Ocean ecosystem. They are filter feeders that primarily consume phytoplankton. They can go long periods with no food

Defensive Mechanisms: primarily use swarming as a defensive mechanism, which confuses smaller predators

Unique Structures: they possess bioluminescent organs that produce light. Additionally, krill have compound eyes and can shrink their bodies in response to low food availability. 

What Makes Them Unique: they have massive numbers and the ability to survive harsh conditions

Classfication:

• Kingdom: Animalia

• Phylum: Arthropoda

• Class: Malacostraca

• Order: Decapoda

• Family: Palinuridae

• Genus: Panulirus

  
  

  
  

• Related Animals:

• Crabs

• Shrimp

• True lobsters

• Other crustaceans

• 
  

• 
  

  Habitat:

• Found in warm oceans waters

• Tropical and subtropical regions

• Coral reefs

• Rocky crevices

• Grass sea beds

• Carribean sea,Pacific ocean

  
  

  
  

  
  

• Life style and diet:

• Nocturna scavengers

• Small crustaceans

• Algae

• Dead animals

• Mollusks

  
  

  
  

  
  

• Defensive/offensive mechanisms

• Sharp spine

• Power tail flips

• Antennae whipping

  
  

  
  

• Unique structures

• Long thick antennae

• Exo-skelton covered in spines

• Renegenrative limbs

Classification: Phylum- Arthropoda, Class- Malacostraca, Order- Decapoda, Infraorder- Brachyura

Relatives: ghost crabs and mangrove crabs

Home: Coastlines, salt marshes, tidal flats

Lifestyle: Diet- algae, bacteria, fungus, and detritus

Defense/offense: Big hand

unique structure: Big hand

Fun fact: he as a big hand

Classification: Phylum Arthropoda. Subphylum Chelicerata. Order Xiphosura.

Relatives: Spiders and scorpions

Habitat: Atlantic Ocean

Lifestyle: Prey consists of slow invertibre Alge and organic matter. Hunting consists of searching around with their legs and breaking prey up with their legs and feeding their mouth with their appendages

Unique structure: They have a conjoined, with three different sections. Spines on the rear abdominal region for protection from other animals.

Facts: Horseshoe crabs have blue blood containing hemocyanin and a copper filled protein that transports oxygen. They can also walk on 10 legs and use their last pair called the chelicera to move food to their mouth.

Uca

They are closely related to ghost crabs (genus Ocypode)

Phylum: Arthropoda

Class: Malacostracans

Order: Decapods

Infraorder: Brachyura

Where They Live

They primarily inhabit coastal salt marshes, mud-flats, and sandy or muddy beaches near water. Often found along the edges of marsh creeks and shallow salt marshes. They live in burrows, in which they dig in either the sand or mud

Lifestyle

They eat algae, bacteria, and decaying plant/animal matter found in the mud

How they eat is by using their small claw to pick up bits of sediment from the ground and then sift through it with their mouth parts, extracting any food like algae, bacteria, or decaying plants. Then they discard the remaining sand in small balls

They hunt by using their claws to gather and process food

Defensive Strategies:

Large Claw:

The super-sized claw, primarily used for attracting females, also functions as a defense against other crabs and predators, serving as a mechanical deterrent. 

Visual and Auditory Cues:

Fiddler crabs are vigilant and will flee into their burrows upon detecting shadows, movement, or loud noises, demonstrating an awareness of potential threats. 

Herd Formation:

In the presence of a predator, fiddler crabs may form groups, potentially confusing the predator and reducing the likelihood of a single crab being targeted. 

Thanatosis (Feigning Death):

In the last resort, fiddler crabs might adopt a rigid, immobile posture to avoid being eaten by predators that rely on movement. 

Burrow Defense:

Burrows serve as crucial shelters, protecting fiddler crabs from various threats like predators and tidal inundation

Offensive Strategies:

Large Claw (Combat):

The large claw is also used offensively in confrontations with other male crabs, especially during territorial disputes or competition for mates. 

Burrow Acquisition and Defense:

Males will actively defend their territories, including burrows, to attract females and ensure reproductive success. 

Coalitions:

Fiddler crabs may cooperate with neighbors to defend their territories against intruders. 

Pillar Building:

Some species construct mud and sand pillars around their burrows, potentially serving as deterrents to other crabs or as part of courtship displays. 

Interesting Facts!

Claw Differences:

Male fiddler crabs have one large claw and one small claw, while females have two small, equal-sized claws. 

Mating Rituals:

Males wave their large claw at females to attract them and use sound produced by claw movement and stamping their legs. 

Regeneration:

If a male loses its large claw, it can regenerate a new one, and in the meantime, the smaller claw will grow larger. 

Diet and Ecology:

Fiddler crabs are detritivores, feeding on dead organic matter, and their burrowing and feeding activities help cycle nutrients in the marsh. 

Stalked Eyes:

Fiddler crabs have eyes on stalks, allowing them to see in all directions and detect predators from a distance.

"Violinist" Name:

The large claw of the male fiddler crab, combined with its waving motion during courtship, gives it the nickname "violinist". 

High Densities:

Fiddler crabs can live in very high densities in salt marshes, with up to 70-200 crabs per square meter. 

Sensitivity to Light Polarization:

Research from the University of Bristol has found that fiddler crabs are sensitive to the polarization of light, which may help them with various visual tasks, including detecting rivals

Relatives - They are related to Shrimp, Crab, Lobsters and Crayfish.

Habitat - Rock Pools and shallow waters down around 40m deep. They normally hide under stones.

Lifestyle - They are scavengers meaning they eat whatever they find, from decaying seaweed to dead mussels

Defense mechanisms - Camouflage and Prawns have spines on both ends of the bodies that can detect predators

Unique structures - The rostrum is a prominent, upturned spike located on the dorsal part of the carapace, in front of the eyes, it has distinct dorsal and ventral teeth, helping it distinguish from other prawn species

Other facts - Female common prawns carry their fertilized eggs around, carrying up to 4,000.

Closely related to pillbugs and sow bugs!

Live in a huge variety of habitats, from coastal regions to the deep sea.

Mainly carnivores but feeding habits vary. Many are scavengers, parasites, predators or filter feed on small organisms.

Often, rolling into a ball is their main defense, using their exoskeleton as armor.

All isopods share arthropod characteristics, as well as all having four sets of jaws, two pairs of antennae, and compound eyes.

There are an estimated 10,000 species of isopod! They're very diverse.

• Bathynomus

Classification

• Phylum: Arthropoda

• Class: Malacostraca

• Order: Isopoda

Animal relations

• Crustaceans: crabs, lobsters, etc.

• Terrestrial Isopods: roly-polies, pillbugs, etc.

Habitat

• Deep Sea

• Prefer muddy or clay bottom

Lifestyle

• Scavengers: Crawl around on bottom of the seafloor to find food that fell

  • Fish, crabs, marine snow or worms, whale fall, etc.

Defensive/Offensive

• Curl into a ball w/ only hard exoskeleton showing

Unique Structures

• Females have a marsupium, a pouch to carry their young

• Long antennae, half the length of their body

Interesting Information

• More than 10,000 species of Isopods

• Marine isopods have swimming limbs called pleopods

• Giant Isopods have a slow metabolism, allowing them to live for years without food

• Giant Isopods can be an example of deep-sea gigantism

Classification which is specified below for each animal: Malacostracans

What kind of animals they are related to: squat Crab, porcelain crabs, and king crabs

Habitat where they live: land hermit crabs living near coastlines in tropical regions and marine hermit crabs inhabiting various coastal areas, including bays, beaches, and mudflats

Lifestyle, including what they eat, how they eat, how they hunt, or how they scavenge: Hermit crabs do not actively hunt, but rather forage and scavenge for food, often in a group

Any particular defensive or offensive mechanisms they possess: Hermit crabs primarily use their shells for defense, retreating inside when threatened. They may also use their claws for defense or aggression during shell fighting. Some hermit crabs also employ camouflage and clustering as defensive strategies

Any structures unique to that particular animal: soft, spirally curved abdomens

Any other unique or interesting information about the animal: They're closely related to squat lobster

Kingdom: Animalia

Phylum: Arthropoda

Subphylum: Crustacea

Class: Malacostraca

Order: Stomatopoda​

Mantis shrimps are not true shrimp but belong to their own distinct order, Stomatopoda. They are more closely related to crabs and lobsters than to shrimp

Mantis shrimps inhabit shallow, tropical, and subtropical marine environments. They are commonly found in the Indo-Pacific region, including the Great Barrier Reef, as well as in the eastern Pacific and western Atlantic Oceans. These creatures often reside in burrows or crevices within coral reefs, rocks, or sandy substrates, which they use as both hunting grounds and protective shelters.​

Mantis shrimps are carnivorous predators with two primary hunting strategies:​

Spearers: Equipped with spiny, barbed appendages to impale soft-bodied prey such as fish, squid, and worms.

Smashers: Possess club-like appendages to bludgeon hard-shelled prey like snails, crabs, and mollusks.​

They are solitary and territorial, often ambushing prey from their burrows with lightning-fast strikes.

The mantis shrimp's raptorial appendages can strike with incredible speed and force, accelerating as fast as a bullet. This strike creates cavitation bubbles that collapse with a shockwave, capable of stunning or killing prey even if the initial hit misses. Their powerful claws can break aquarium glass and are used both for hunting and defense.

Eyes: Mantis shrimps have some of the most complex eyes in the animal kingdom, capable of detecting polarized light and a broad spectrum of colors, including ultraviolet. Each eye operates independently and has trinocular vision, allowing precise depth perception.

Exoskeleton: Their club-like appendages are composed of a highly durable material that absorbs and dissipates the energy from their powerful strikes, inspiring research into advanced materials for armor and aerospace applications.​

Longevity: Some species can live up to 20 years in the wild.

Reproduction: Certain species are monogamous, with pairs sharing and defending a burrow.

Cultural Impact: Their striking appearance and abilities have made them popular subjects in marine biology and popular culture.​

• Pagurus bernhardus or Coenobita clypeatus.

  
  

Classification

• Kingdom: Animalia

• Phylum: Arthropoda

• Subphylum: Crustacea

• Class: Malacostraca

• Order: Decapoda

• Superfamily: Paguroidea

Related Animals

• Crabs

• Lobsters

• Shrimp

Habitat

• Saltwater environments like tide pools, coral reefs, and seashores.

• Land hermit crabs live on coastal land areas, usually in warm, humid tropical environments.

• They require access to water to keep their gills moist for breathing.

  
  

Lifestyle

• Diet: Omnivorous scavengers.

• They eat algae, dead fish, plankton, fruit, decaying plant matter, and sometimes small invertebrates.

• Feeding Method: They use their small pincers to pick food and bring it to their mouths.

• Behavior: Mostly nocturnal, active scavengers.

Defense Mechanisms

• Shell Borrowing: Hermit crabs have soft abdomens, so they use empty snail shells to protect themselves.

• When threatened, they retreat into their shells and block the entrance with their claws.

• Some species carry sea anemones on their shells for extra protection—benefiting from the anemone’s stinging cells.

Unique Structures

• Soft, spiral-shaped abdomen that fits inside snail shells.

• One claw is usually larger than the other (called the cheliped)—used for defense and sealing off the shell.

• Modified gills that allow them to breathe air mostly land hermit crabs

Interesting Facts

• Hermit crabs do not make their own shells they depend on empty gastropod shells and must find larger ones as they grow.

• They sometimes fight over shells, and "shell swapping" can happen among groups.

Phylum: Arthropoda

Subclass: Cirripedia

Related Animals: Crabs, lobster, and shrimp

Habitat: Rocky shores/cliffs (intertidal zone)

Lifestyle:

• Food: Plankton and Detritus

• How they eat: They use their leg/appendages to grab food

Physical defense mechanism: strong stalks and calcareous plates to deter predators and withstand waves

Unique Structures: Flexible stalk that attaches to surfaces

Arthropoda, Malacostraca, Decapoda, Anomura

Squat lobsters

Forests, marshes, and coastal areas mainly on land near the shoreline in tropical regions

Small fish, invertebrates like worms, plankton and floating food particles. Omnivorous. Scavenge their food.

Use a shell to defend themselves

Soft backs that they must protect with a shell that they scavenge.