Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
SlideShare a Scribd company logo

fish predation

•Download as PPTX, PDF•
•

Marine fish employ a variety of behavioral and morphological adaptations to avoid predation. Behaviorally, fish school together for safety in numbers, migrate to safer habitats, and care for offspring. Morphologically, fish have body shapes and colors that camouflage them, strong fins and scales for defense, senses like lateral lines to detect predators, and some can even shock or fly away from threats. Both behavioral and physical adaptations are crucial for the survival of prey fish and maintenance of ecosystem balance.

1 of 13
BEHAVIORAL AND MORPHOLOGICAL PREDATOR AVOIDANCE TECHNIQUES IN MARINE FISH WESONGA SAMWEL SNAT/FAS/M/002/20
What is predation • It is the attacking/preying/killing of other animals for the purpose of food. • Predatory fish eat live animals as their food, usually other fish. • Intra specific (cannibalism) & interspecific predation • Anti-predation – protecting against predation; hindering predators • Predator defenses – a set of traits and mechanisms by which prey avoid being detected, recognized, subjected or consumed • The anti-predator behavior differ in terms of predator related factors like the size, habitat use, density, diel activity and hunting strategies if the predators.
Significance of predation • Predation is one of the key factors governing patterns in natural systems • Adjustments of prey behaviors in response to a predator stimulus can have important ecological implications • For a healthy ecosystem, the environment has to balance the predator-prey relationship (Geraghty, 2012). • This is to ensure survival of both the predatory and prey species; • the skill sets of predators and the defense of the preys are both vital in maintaining a stable ecosystem. • Each party must adapt to the changing environment to ensure its survival lest they succumb
• Predator defenses are of major importance during all phases of fish’s life especially to young fishes • During larval period when survival is the ultimate goal for individual fish to reach maturity and have the opportunity to reproduce. • With such high stakes, a variety of development characteristics, morphological, behavioral, and experiential predator avoidance techniques are key to fish’s survival • Older fish are increasingly able to respond to external stimuli and can detect and react to predators or join conspecifics in common defense • Both morphological and behavioral adaptations aids in escaping or protection from predatory fish
Behavioral predator avoidance • Schooling • Common behavioral pattern among prey fishes • About 80% of all fish species school as juveniles and roughly 20% school as adults • The concept of “safety in numbers” plays a fundamental role in schooling behavior. • A predatory fish presented with a single item of food receives only one set of stimuli which direct it to its prey • Protection in schooling appears when a predator fish is confronted with a school of fish which causes it to receive numerous conflicting stimuli which block the feeding response
• Parental care • Fingerling and juveniles are at a greater verge of getting preyed on than larger mature fish. • Parental care for the eggs and young is a vital protection measure for this small fish. • For mouth-brooders they carry the eggs around in their mouth for protection and migrate to special brooding ground then eventually the young are left at sublittoral sheltered nursery ground to AVOID predators. • Migration • Fish migrate from places infested with predators or places they are more vulnerable to be caught by in search of safer grounds. • Some species may migrate up the rivers to spawn at grounds where their young are safe. I.e. Anadromous. • The young often remain upstream in shallow water where they are more likely to escape predation by large fish (Lowe McConnell, 1975). • Prey fish also gain some protection by descending to dimmer lit zones during the day where they cannot be easily seen by predators.
• Staying at home • Fishes like tilefishes reside in self-made burrows to where these fishes retreat when they detect danger. • Most often the burrows are rather elaborate and have several entrances and exits hence a predator cannot just watch one opening and be ensured of cornering its prey. • Other do not require burrow as they can quickly bury themselves in sandy bottoms.
Morphological adaptations predator avoidance • Strong fins, spines and armored scales • Predatory fishes are not able to consume fish with strong bony fishes with fear of being hurt or wounded by the piercing fins. • The strong fins also help the prey fish to maneuver and swim fast to escape predator fish. • Balloonfishes and pufferfishes can inflate their bodies by swallowing a lot of water, erecting a number of very sharp spines. • The rigid and sharply pointed spines give an attacker an unpleasant mouthful of “nails and needles” instead of an easy meal.
•Body shape and size • Prey can escape from its predator depending on relative body size difference between them • which is mainly imposed by morphological restriction of the predator’s mouth width also known as gape size limitation. • Predatory fishes are able to consume cylindrical-shaped fishes which are of a larger size than the deep bodied fish which they may also prey upon. • Most prey fish have a streamlined body shape that reduces water resistance to enable the animal to move faster in water and escape the predator (Fu et al., 2015)
• Camouflage • It is the technique used by marine fish of resembling and blending in with their surroundings. • It involves body coloring, body shape, and/or behavior which prey fish use to confuse, distract, startle, or hide from predators. • It is used by both sides in the battle for survival. • Prey animals use camouflage to remain undetected by their predators; predators use camouflage to sneak up, unseen, by their prey. • The three kinds of camouflage are 1. Color resemblance-When the fish’s color resembles its natural environment. This helps the fish to not be seen while still in plain view 2. Counter shading • This is kind of Camouflage designed to hide fish’s three-dimensional form. • One side of the fish is dark and the other is light serving as a camouflage. • It’s seen in species in coastal and open ocean habitats like the Atlantic Bluefin Tuna (Thunnus thynnus). • The dark dorsal part blends them with the substrate or deeper water bellow when viewed from above. The light dorsal part blends the fish with water and light from the sky above them when viewed from bellow. 3. Disruptive coloration • This involve markings on the fish that disguise the fish among its surroundings by leading the eye away from its shape or obscuring the contour of its body. Copper band butterflyfish (Chelmon rostratus) and Picasso triggerfish (Rhinecanthus aculeatus) (Mashall, 2019)
• Senses • Some prey fish have very developed sensory systems that aid in detecting a predator presence or location hence avoiding them. • This is very useful because most prey fish rely on escape as their form of protection. • The most important sense fish use is sight and feeling/hearing. • Fish hear through otoliths which have cilia that are stimulated by vibrations in the water. • Another way fish can hear is through lateral lines which also detect movements and vibrations in the water (Braun et al., 2008). - Mechanoreception • Warning signal • The warning signals may come in many forms like chemical alarm pheromones and distress sounds • According to Jan Smith 1992, one of the logical reasons that would reconcile the lack of observation in this paradigm is this is one of the adaptation of prey fish to give out predator deterrents.
• Venom • Marine fish including stingrays, chimaeras, Scorpionfishes, lionfishes and stonefishes have venomous spines with poison gland which produce toxins. • They use this as a form of defense against predators. • When threatened these species can quickly lunge forward and use these spines as venom- injecting needles to repel threats. • Flying • Over 50 species of flyingfishes have the ability to fly/ glide above the surface of the ocean to escape predators. • They are equipped with enlarged pectoral fins and enlarged lower lobe of the tail that they use to “jump” out of the water and then glide through the air over considerable distances. • Their greatly enlarged pectoral fins creates an airfoil similar to an airplane wing providing lift and enabling these fishes to glide. • Their enlarged pelvic fins also provide additional lift and their enlarged lower lobe of the tail works like an outboard motor with the sideways motion of the tail enabling the fish to gain height and extend the duration of the flight (up to 100m long and 3m high).
• Electric shocks • Fish like electric rays are not fast swimmers nor do they poses poisonous spines like stingrays • They are equipped with specialized electricity-producing organs that can unleash powerful electric shocks that help these rays protect themselves and stun prey. • They just need to be sure the prey is within the electrical field created when they unleashes a jolt of electricity.

More Related Content

fish predation

  • 1. BEHAVIORAL AND MORPHOLOGICAL PREDATOR AVOIDANCE TECHNIQUES IN MARINE FISH WESONGA SAMWEL SNAT/FAS/M/002/20
  • 2. What is predation • It is the attacking/preying/killing of other animals for the purpose of food. • Predatory fish eat live animals as their food, usually other fish. • Intra specific (cannibalism) & interspecific predation • Anti-predation – protecting against predation; hindering predators • Predator defenses – a set of traits and mechanisms by which prey avoid being detected, recognized, subjected or consumed • The anti-predator behavior differ in terms of predator related factors like the size, habitat use, density, diel activity and hunting strategies if the predators.
  • 3. Significance of predation • Predation is one of the key factors governing patterns in natural systems • Adjustments of prey behaviors in response to a predator stimulus can have important ecological implications • For a healthy ecosystem, the environment has to balance the predator-prey relationship (Geraghty, 2012). • This is to ensure survival of both the predatory and prey species; • the skill sets of predators and the defense of the preys are both vital in maintaining a stable ecosystem. • Each party must adapt to the changing environment to ensure its survival lest they succumb
  • 4. • Predator defenses are of major importance during all phases of fish’s life especially to young fishes • During larval period when survival is the ultimate goal for individual fish to reach maturity and have the opportunity to reproduce. • With such high stakes, a variety of development characteristics, morphological, behavioral, and experiential predator avoidance techniques are key to fish’s survival • Older fish are increasingly able to respond to external stimuli and can detect and react to predators or join conspecifics in common defense • Both morphological and behavioral adaptations aids in escaping or protection from predatory fish
  • 5. Behavioral predator avoidance • Schooling • Common behavioral pattern among prey fishes • About 80% of all fish species school as juveniles and roughly 20% school as adults • The concept of “safety in numbers” plays a fundamental role in schooling behavior. • A predatory fish presented with a single item of food receives only one set of stimuli which direct it to its prey • Protection in schooling appears when a predator fish is confronted with a school of fish which causes it to receive numerous conflicting stimuli which block the feeding response
  • 6. • Parental care • Fingerling and juveniles are at a greater verge of getting preyed on than larger mature fish. • Parental care for the eggs and young is a vital protection measure for this small fish. • For mouth-brooders they carry the eggs around in their mouth for protection and migrate to special brooding ground then eventually the young are left at sublittoral sheltered nursery ground to AVOID predators. • Migration • Fish migrate from places infested with predators or places they are more vulnerable to be caught by in search of safer grounds. • Some species may migrate up the rivers to spawn at grounds where their young are safe. I.e. Anadromous. • The young often remain upstream in shallow water where they are more likely to escape predation by large fish (Lowe McConnell, 1975). • Prey fish also gain some protection by descending to dimmer lit zones during the day where they cannot be easily seen by predators.
  • 7. • Staying at home • Fishes like tilefishes reside in self-made burrows to where these fishes retreat when they detect danger. • Most often the burrows are rather elaborate and have several entrances and exits hence a predator cannot just watch one opening and be ensured of cornering its prey. • Other do not require burrow as they can quickly bury themselves in sandy bottoms.
  • 8. Morphological adaptations predator avoidance • Strong fins, spines and armored scales • Predatory fishes are not able to consume fish with strong bony fishes with fear of being hurt or wounded by the piercing fins. • The strong fins also help the prey fish to maneuver and swim fast to escape predator fish. • Balloonfishes and pufferfishes can inflate their bodies by swallowing a lot of water, erecting a number of very sharp spines. • The rigid and sharply pointed spines give an attacker an unpleasant mouthful of “nails and needles” instead of an easy meal.
  • 9. •Body shape and size • Prey can escape from its predator depending on relative body size difference between them • which is mainly imposed by morphological restriction of the predator’s mouth width also known as gape size limitation. • Predatory fishes are able to consume cylindrical-shaped fishes which are of a larger size than the deep bodied fish which they may also prey upon. • Most prey fish have a streamlined body shape that reduces water resistance to enable the animal to move faster in water and escape the predator (Fu et al., 2015)
  • 10. • Camouflage • It is the technique used by marine fish of resembling and blending in with their surroundings. • It involves body coloring, body shape, and/or behavior which prey fish use to confuse, distract, startle, or hide from predators. • It is used by both sides in the battle for survival. • Prey animals use camouflage to remain undetected by their predators; predators use camouflage to sneak up, unseen, by their prey. • The three kinds of camouflage are 1. Color resemblance-When the fish’s color resembles its natural environment. This helps the fish to not be seen while still in plain view 2. Counter shading • This is kind of Camouflage designed to hide fish’s three-dimensional form. • One side of the fish is dark and the other is light serving as a camouflage. • It’s seen in species in coastal and open ocean habitats like the Atlantic Bluefin Tuna (Thunnus thynnus). • The dark dorsal part blends them with the substrate or deeper water bellow when viewed from above. The light dorsal part blends the fish with water and light from the sky above them when viewed from bellow. 3. Disruptive coloration • This involve markings on the fish that disguise the fish among its surroundings by leading the eye away from its shape or obscuring the contour of its body. Copper band butterflyfish (Chelmon rostratus) and Picasso triggerfish (Rhinecanthus aculeatus) (Mashall, 2019)
  • 11. • Senses • Some prey fish have very developed sensory systems that aid in detecting a predator presence or location hence avoiding them. • This is very useful because most prey fish rely on escape as their form of protection. • The most important sense fish use is sight and feeling/hearing. • Fish hear through otoliths which have cilia that are stimulated by vibrations in the water. • Another way fish can hear is through lateral lines which also detect movements and vibrations in the water (Braun et al., 2008). - Mechanoreception • Warning signal • The warning signals may come in many forms like chemical alarm pheromones and distress sounds • According to Jan Smith 1992, one of the logical reasons that would reconcile the lack of observation in this paradigm is this is one of the adaptation of prey fish to give out predator deterrents.
  • 12. • Venom • Marine fish including stingrays, chimaeras, Scorpionfishes, lionfishes and stonefishes have venomous spines with poison gland which produce toxins. • They use this as a form of defense against predators. • When threatened these species can quickly lunge forward and use these spines as venom- injecting needles to repel threats. • Flying • Over 50 species of flyingfishes have the ability to fly/ glide above the surface of the ocean to escape predators. • They are equipped with enlarged pectoral fins and enlarged lower lobe of the tail that they use to “jump” out of the water and then glide through the air over considerable distances. • Their greatly enlarged pectoral fins creates an airfoil similar to an airplane wing providing lift and enabling these fishes to glide. • Their enlarged pelvic fins also provide additional lift and their enlarged lower lobe of the tail works like an outboard motor with the sideways motion of the tail enabling the fish to gain height and extend the duration of the flight (up to 100m long and 3m high).
  • 13. • Electric shocks • Fish like electric rays are not fast swimmers nor do they poses poisonous spines like stingrays • They are equipped with specialized electricity-producing organs that can unleash powerful electric shocks that help these rays protect themselves and stun prey. • They just need to be sure the prey is within the electrical field created when they unleashes a jolt of electricity.

Editor's Notes

  1. Marine prey fish incorporate both the antipredator behavior and prey defense strategies associated to the morphological adaptations to ensure high chances of survival
  2. Each fish near the edge of the school is in a continuous lookout, thus helping to protect the rest of the school and are able to quickly react to the escape reaction of the other fish