Topic:Navigation behaviour in Lymnaea stagnalis


Type: Report

Volume: 11 pages

Format: APA


The font should be Times New Roman, and its size 12. Navigation behaviour in Lymnaea is any movement to
detect (food and mate) or avoid predators. My report focus on predator detection in Lymnaea. My

Hypothesis is when lymnaea detects food and at the same time detects a predator, lymnaea may use the

defense behaviour (contract inside their shells or hiding under the rocks) until the predator moves

away; then, lymnaea use the memory behaviur to detect the food place via chemical odour.

General notes:
1- Explanation of proximate vs ultimate mechanisms
Animals do certain behaviours in order to live and continue to live, some of them are able to live in separate families or groups. Behaviour is defined as an action in response to internal or external stimulus in an organism’s environment such as food, parasites, light, and predators. All behaviors lead to the purpose of helping the animal to mate, eat and avoid predators. The origin of behavior is from the genetics, that DNA exists since the birth of the animal and causes for a limited response to what his body can do, or the learning, that appears in animal as result of habituation, and exposure to stimulus more than once during his lifetime, and environment has given the animal enough information and changes behaviour over time to adjust his environment. There are two ways of analyzing behaviour by proximate and ultimate mechanisms. Proximate mechanisms explain how animal behaviour has occurred, and whether the type of response is innate, which may be caused by genes, hormones, muscles, or nerves. It could also be acquired, which may be caused by the organism through its experience. Ultimate mechanisms explain why the organism behaviour happens and behaves in a certain way based on their evolution or history. The fitness of an organism effects the ability to successfully reproduce and evolution of genetic. Adaptation can be defined as a hereditary attribute to ensure the survival of a species through a natural selection process, present in past populations and continuing.
Most effect of behaviour is natural selection that is a process that facilitates certain inherited traits for the chances of survival, reproduction of some individuals, and changing the genetic makeup of the species over time. For the occurrence of natural selection, the population group must have differences, some of which are inherited, and then one makes the organism more competitive. The main principle is that individuals do not develop, but natural selection occurs as an evolutionary change because it changes the genetic makeup of the entire group, which occurs through interaction between individuals and their surrounding environments.
To suppose that you have a group of birds, some of these birds have strong beaks and some of them slightly weak, but individuals with small beaks have a high speed of escape while strong beaks slow, so now we have two hypotheses: Firstly, we put birds in an environment where fruit trees are very cruel, and there are no predators in this environment. Secondly, we put the birds in an environment where predators and trees with normal fruit hardness. The first example, the speed attribute is not effective and does not give a survival advantage. While the beak strength gives a higher priority and survival ability, birds with strong beaks will survive and die with weak beaks, as natural selection favors the strong beak on the weak. The second example, the fruits are normal and do not need strong beaks. While predators are had and will destroy the birds, and the birds have a faster chance of survival than those slow. That means that natural selection will work and prefer the beneficial to the harmful, and the slow will die and remain high speed, but the status of the strength of the beak has nothing to do with survival. The natural election will not interfere. Therefor, natural selection is an indiscriminate selection process for random changes. Evolutionary mutations and pressures are the determinants of evolution rather than organisms adapted to the environment.
2- Proximate Mechanism of Navigation Behaviour in Lymnaea (minimum 3 pages double spaced).
Explain Lymnaea and its habitat (who) also, who are the predators? Crayfish and tench (fish)
Define Navigation Behaviour (what it is?)
Where? Their natural environment, flow and no flow
Examples of when Lymnaea use these types of navigational behaviours? Finding food, finding a mate, avoiding predators, chemotaxis, rheotaxis, chemo-gated rheotaxis (3 types)
How Lymnaea avoid predators? Genes, hormones, nerves, and muscles Mechanistic hypothesis (the mechanism causes the pattern).

3- Ultimate Mechanisms of Navigation Behaviour in Lymnaea (minimum 2 pages double spaced)
Why (evolution + history) Mechanistic hypothesis (the mechanism causes the pattern)

Experiment (adaptationist approach)
• Tests whether behaviour causes a benefit (on a cost).

Survey (comparative approach)
• Tests whether mechanism is comparatively correlated with the pattern.
• Tests whether behaviour exists where the benefit exists.
• Tests whether behaviour does not exist where the benefit does not exist.

– The animal is characterized by its ability to move and move in search of sources of drinking and food, and different ways of moving animals from object to object. Crawling is a way of traveling for animals that do not stretch out.

– Each type of animal has a form of camouflage and predator-avoidance , an adaptation that allows animals to integrate with the surrounding environment, where camouflage increases the chance of an organism surviving by protecting it from predators, giving the animal a greater chance of being able to reproduce successfully And the continuation of life, camouflage is also used by some predators as a fishing tool and increases their chances of getting food easier and more successful, and we will provide the most important information about the phenomenon of camouflage in animals during this article.

– How snail movement and access to their destinations involved in aquatic environments is difficult and a mystery for the observers. Generally, an animal’s direction occurs when it tries to approach and reach sources that may be food, mates or predators. This direction is based on the style of navigation which is the movement of the animal in response to stimuli. The direction of the movement may be deliberate or unintentional depending on the source of the stimulus. This dependence can be chemotaxis (odor), rehotaxis (water current), and phototaxis (light intensity) because snails use odour gradients and ocean currents in navigation strategies. Therefor, the movement of snail may toward food and mates (positive) or away from predators (negative).
– Predator avoidance behaviour is more effective of navigation in Lymnaea stagnalis. It decrease the likelihood that an individual is attacked and should therefore reduce selection on behaviors that enhance probability of escape on attack.
– When Lymnaea senses a predator, they can detect or interpret its distance, physiological change, state and whether it is a food source. Lymnaea has the ability to process information about their predators in their presence such as distance, physiological state, and food selection, sustenance, or food source. Lymnaea detect predators via kairomones and have the ability to … Discussion: “predatory detection” laboratory-reared lymnaea maintained (kept) their capacity to detect crayfish predators via a kairomone. 4155.
– Changes in certain 1)defensive behaviours 2)physiological changes and 3)electro-physiological parameters in (important).
– 1) increased aerial respiratory (breathing) activity when L are at the … interface. 2) when exposed to the effluent (liquid waste) of crayfish.
– Check: Crayfish may be able to crush snail shells with their jaws or claws and maybe they can.
– Lymnaea may detect the scents of certain kinds of predators such as crayfish that can crush their shells and fish that can not crush their shells. When snails sense crayfish, they instinctively jump out of the water to avoid the shell-crushing predators, which means the level of risk is higher and the degree of anti-predator response or predator avoiding behaviour is strong.
– If snails do not have enough oxygen, their shells turn yellow and white and thickness of their shell growth is affected (or impacted). When an organism does not receive enough oxygen, they can experience hypoxic impairment (damage). Pg. 4156. Hypoxia is a deficiency in the amount of oxygen reaching the tissues.
– Snails that sensed predators did not do this. Do this = when they sensed a decrease in Po2, organisms initially increased their behaviours, (the compensatory response = compensate) such as heart rate and respiratory rate to counteract the fall in Po2.
– Chemical cues alter neuronal function in Lymnaea. Neuronal and molecular changes … operant conditioning of the respiratory behaviour have been demonstrated in RPeD1. Pg. 4156. Neuronal mechanisms of fear conditioning…
 Snails contract inside their shells when they are upside down (righting response). 4156.
 When snails are upside down or turned over, their response time decreases when they sense or perceive a predator or threat (crayfish) than ……
 Vigilance (prey respond appropriately to factors) predator density, distance, size of predator, prey vulnerability (weakness) pg. 4156
 Shadow response. 4156
 Are capable of ….. multiple defensive responses
 Different habitats that have multiple predators cause increased vigilance and level of predator threats. Snails are more vigilant when there are multiple predators in their habitat and the threat level is increased.
 RPeD1 related to breathing, neurobiological changes 1- respiratory behaviour 2- full-body withdrawal behaviour …..see Susan’s note pg. 3
 When snails sense predators, their peripheral nervous system alters (changes) and may be important in mediating aerial respiratory behaviours. Q
 L. detect predator kairomones and respond in the appropriate manner (way) to decrease the threat of predators.
 Kairomones may be present in the urine of crayfish. See pg. 4157. L. have been shown to be necessary for long-term memory formation, reconsolidation, extinction, and forgetting. Kairomones =predator-derived chemical cues. Pg. 4150
 Even though naïve snails that do not have any experience with predators (or predators are not found in their environment), they can recognize predators and respond with multiple defensive behaviours. It is therefore likely that snails have the ability to process and detect predator threats from multiple sources. Pg. 2137.
 It is suggested that the predator threat may be lower in fishless populations. Pg.2138.
 Observed decrease …use of the refuge in resporse to tench cues….most likely an arte fact of the increase in craul out response.
 Exert more energy when jumping out of the water ….. hiding takes less energy or exertion than jumping out of the water.
 Crawl out behaviour is the main response to tensh kairomones. Pg. 2137.
 Use of a refuge may occur in response to fish predators. Pg. 2136.
 Crawl-out behaviour has been found to be the main anti-predator response to tench cue. Hiding place (under a rock) = refuge. Pg. 2136.
 The snail goes away or moves away from the predator slowly. Lymnaea may have a decreased response when a new species is introduced to their environment. Pr.1. have low dispersal abilities.
 An innate adaptation to predatory fish cues: not affected at all adapts the same behavioural evolutionary mutations determinants of evolution.
 Snails generally have low responses to predatory fish cues that they are not normally exposed to. Over generations, their anti-predator response may have mutated to no longer recognize potential predatory species. However, there are likely consequences with having a reduced avoidance response in environments without predators such as the loss of sexual ornamentation or plasticity responses.
 The consequences for maintaining a high degree in ….Lymnaea = experience predators when they are introduced to predator avoid. It is possible that there are consequences with having a high anti-predator response rate to fish cues when they are not present …(continued). Although it is (perplexing) curious that snails maintain a response rate in low risk populations.
 When flooding occurs, environments without any predators could be invaded by predatory fish as the population with fish and without are located on a flood plain and are closely situated. Potential for gene flow.
 When high and low response populations merge there could be a possibility for gene flow between populations thus maintaining a degree of anti-predator behaviour.
 When snails do not respond appropriately to predators, there is an increased potential impact on their fitness. Occasional encounters with predators could result in the sustainment of anti-predatory behaviour.
 Lymnaea from the lab reproduce at a faster rate than those which reproduce in environments where predators increase the population.
 Because of the ongoing threat level and presence of predators, snails in the first group reproduce more quickly to adapt to local predator regimes.
 Lymnaea in environments with no or low predators, reproduce at a slower rate than those where predators are present.
 The genes do not change but the genetic response does.
 Lymnaea raised in labs (or laboratories) have a ……
 The higher the concentration of predators, the higher the crawl out responses or response rates. In a lab the response rate is lower or slower.
 Lymnaea have the ability to adapt to local predator regimes and do not solely rely on plasticity to change their behaviour.
 Alternative explanation: snails are sensitive to predators and not have a specific response to predators. Their awareness of predators may be due to conditions which affect their behaviour.
 When low risk populations are exposed to many invertebrate predators, their responses may be similar to anti-predator responses to other taxa.
 Their anti-predator response time for low risk populations could take longer depending on the type of predator.
 Habitat could have an influence on the avoidance response in snails and their varied behaviour observed when predators are present.
 Microevolution is responsible for the variation between populations and is a consequence of natural selection responding to anti-predatory behaviour.
 Snails living in environments where there is a high predation risk are not always able to relocate to areas which have a low predation risk and, as a result, could develop adaptive responses to local predators.
 Snails possess an innate ability to relate predation cues and degree of risk perception. This enables snails to adjust their long-term anti-predatory responses to their environment.

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