1. Defense Mechanisms
2. Types of Defenses
3. Physical Defenses
4. Color Defenses
5. Chemical Defenses
6. Behavioral Defenses

Defense Mechanisms

1. Mechanisms that protect the prey from predators
2. Prey evolves new defenses to defeat predator
3. Predator evolves new ways to circumvent new prey defenses

Types of Defenses

1. Definition: Physical defenses are anatomical mechanisms that protect prey from predators.
2. Definition: Chemical defenses are mechanisms involving chemicals that protect prey from predators.
3. Definition: Color defenses are mechanisms involving color that protect prey from predators.
4. Definition: Behavioral defenses are mechanisms involving activities that protect prey from predators.

Shells

1. Many marine organisms produce a hard shell in which they live.
2. They can extend themselves from the shell opening to carry out a variety of life functions but will withdraw to safety at the slightest hint of danger.
3. Examples of organisms that have shells:

• Snails
• Clams
• Serpulid worms

Borrowed Shells

1. Some marine organisms borrow a shell after the producer has died. They can take up residence in the shell and use it like their own.
2. Since they do not produce shell material, the shell does not grow along with them and they must change to a larger shell as they grow.
3. Examples of organisms that borrow shells:

A. Hermit Crabs

Exoskeletons

1. Many marine organisms produce an exoskeleton that surrounds and protects them.
2. The exoskeleton is outside the skin and in some ways is similar to a shell.
3. Examples of organisms that have exoskeletal armor:

• Corals
• Bryozoans
• Crustaceans

Endoskeletons

1. Many marine organisms produce an endoskeleton that surrounds and protects them.
2. The endoskeleton provides protection but lies under the skin.
3. Examples of organisms that have endoskeletal protection:

• Boxfish
• Seastars
• Sea Urchins
• Sea Turtles

Sharp Spines

1. Many marine organisms have spiny outgrowths of their skeleton or skin that deter predators.
2. Examples of organisms with sharp spines:

• Sea Urchins
• Crown of Thorns Star
• Surgeonfish
• Angelfish

Inflation

1. Some marine organisms can swallow seawater and inflate their bodies so that they are more difficult to swallow.
2. Some combine inflation and spines creating a prickly mouthful.
3. Examples of organisms that can inflate their bodies:

• Puffers
• Balloonfish
• Porcupine Fish

Organs for Clinging

1. Suction
2. Examples of organisms that have organs that cling by suction:

• Molluscan foot
• Echinoderm tube foot

1. Cement and byssal glands for attachment
2. Examples of organisms that have organs of attachment:

• Oyster
• Barnacle
• Mussel

Electric Organs

1. Electric Shock
2. Examples of organisms that have electric organs:

• Electric Eels
• Torpedo Rays
• Star Gazers

Sacrificing Body Parts

1. Autotomy
2. Examples of organisms that sacrifice body parts:

• Crabs
• Brittle Stars

Evisceration

1. Evisceration
2. Examples of organisms that eviscerate:

• Sea Cucumber

Stinging Cells

1. Cnidarians have nematocysts which sting other animals
2. Nematocyst poaching nudibranchs use nematocysts from the cnidarian prey they eat for their own protection

Poison Tipped Spines

1. Some animals tip their spines with poison
2. Examples of organisms that use poison spines:

• Fireworms
• Lionfish
• Scorpionfish
• Stingray

Poisons in Skin and Flesh

1. Some animals produce poison in their skin and flesh
2. Examples of organisms that have poisonous bodies:

• Dinoflagellates (neurotoxin)
• Seaweeds (alkaloids)
• Nudibranchs
• Sea cucumbers
• Puffers (tetrodotoxin)
• Moses Sole

Chemical Releases

1. Some animals release poison into the water
2. Examples of organisms that release poisons:

• Octopus
• Squid
• Sea Hare

Mucus Protection

1. Some animals produce mucus barriers that prevent their scent from spreading
2. Examples of organisms that produce mucus barriers:

• Parrotfish (mucus sleeping bags)

Snares

1. Some animals produce entagling mucus snares
2. Examples of organisms that produce mucus snares:

• Sea cucumbers (polian vesicles)

Color Patterns

1. Permanent body colors
2. Altering body colors
3. Chromatophores=Cells that change color intensity

Camouflage

1. Mimicing background
2. Color matches background
3. Modified fins and scales to alter outline

Countershading

1. Dark above and light below
2. Viewed from above against dark background of deep water
3. Viewed from below against light background of sky

Disruptive Contrast

1. Contrasts strongly with tone of background
2. Observer tends to see pattern and not the fish

Confusing Display

1. Fooled by color or shape
2. Eyespots at the rear make it difficult to determine which is the vulnerable head
3. Prey looks bigger than it actually is

Startle Display

1. Suddenly reveals a dramatic display to startle predators
2. Light Flashes of comb jellies and dinoflagellates
3. Dynamic display of octopus

Warning Coloration

1. Some animals are brightly colored to advertise they are dangerous
2. Observer will avoid advertiser if forewarned
3. Examples of organisms that advertise they're dangerous:

• Nudibranchs
• Lionfish

Mimicing Toxic Species

1. Some animals are brightly colored to match organisms that advertise that they are dangerous
2. Batesian Mimicry: the mimic is non-toxic
3. Mullerian Mimicry: the mimic is also toxic

Fleeing

1. Fast swimming
   • Fishes
2. Jet propulsion
   • Scallop (rapid openi ng and closing of shells)
   • Octopus and squid (rapid contraction of water filled mantle)
3. Explosive flipping
   • Fishes (body straightening of body: C-shape--> I-shape)
   • Crustaceans (rapid contraction of telson)
   • Cockle (rapid straightening of foot)
   • Anemone (rapid extension of pedal disc)

Directed Movements

1. Definition: Thigmotaxis is a directional movement in regards to touch
2. Definition: Phototaxis is a directional movement in regards to light
3. Examples of organisms that have directed movements
   • Rock Slider Crabs
   • Brittle Stars

Directed Movements

1. Definition: Thigmotaxis is a directional movement in regards to touch
2. Definition: Phototaxis is a directional movement in regards to light
3. Examples of organisms that have directed movements

• Rock Slider Crabs
• Brittle Stars

Contraction and Withdrawal

1. Decreasing the length of the body by muscular contraction in order to withdraw into a shell, tube, borrow or other hiding place.

• Anemone contraction (nerve net)
• Fan worm withdrawal (giant axons)

Crypsis

1. Definition: Crypsis is a hiding behavior
2. Definition: Hiding is a process of situating in a location that is difficult to detect
3. Definition: Burrowing is a process of digging into soft sediments
4. Definition: Boring is a process of drilling into rock or shell
5. Definition: Nestling is a process of occupying an abandoned boring or burrow made by another organism

Decorating

1. Definition: Covering with bits of seaweeds and sessile animals
2. Blends in with surroundings

Schooling

1. Definition: Schools are aggregations of fish varying in size from a few to enormous populations extending over several square kilometers
2. Usually monospecific and of similar ages and sizes
3. Members line up parallel, swim in the same direction and maintain fixed spacings (use their lateral lines to detect postion)
4. Dart in all directions when threatened then reform ranks

Schooling as Protection

1. Makes the search for prey more difficult
   • Prey in one spot not many
   • Lowers chances of encounters
2. Makes the capture of prey more difficult
   • Confusing movements
   • Hard to single out one prey