Blind Cavefish

This lab was conducted with the purpose of confirming the trait of homeostasis among goldfish. During the experiment, it was recorded that the fish would increase gill movement when placed in colder water two out of the three trials. However, the results showed no significant difference in gill movement in various temperatures of water. This has very little effect on the broad field of science since our only three trials were performed and may have included human error in the trials.

Background knowledge demands: For this book, students must know what fish and scales are. They will also need to know that fish live under the sea.

3a. Body more than five times as long as broad; front edge of dorsal fin far

- To test this hypothesis my experimental approach would be testing different bodies of water or testing one and just testing different areas while tracking the fish.

In marine mammal biology a large portion of the study is dedicated towards the study of adaptations to the marine environment. By comparing the anatomy between marine mammals and terrestrial mammals scientists can better understand evolutionary history of how these two categories of mammals diverged from one another. The purpose of this lab was to study the anatomy of different marine and terrestrial mammals and compare their similarities and differences in homologous traits and how adaptations were made specifically for marine mammals to survive the aquatic environment. To accomplish this bones of different species of animals were studied since these structures serve as the basis for comparison across species as well as an indicator of each animal’s individual morphology and physiology. A standard measurement protocol for bones of particular regions of the skeleton was established with emphasis on length versus width ratio as well as it’s overall size relative to its more complex features, i.e. humerus length versus hand length.

This investigation was constructed to determine how the Acorn Barnacles respond when the current is changed in their environment. The hypothesis was that if barnacles are placed in a small cup and the current of the water changed, then the barnacle activity will decrease because the current with slow them down. The outcome of this investigation supported the hypothesis.

The blind Mexican cavefish are a group of fish of the same species as the Mexican tetra. Despite the similar genetic makeup of these groups of fish, their outward appearance is a completely different story. Most likely the main difference is that the cavefish have lost the pigmentation in their eyes and gone blind. Researchers believe the reason behind this is the cavefish are simply adapting to living in perpetual darkness by losing their sight. Despite the fact these fish seem to be undergoing regressive evolution, I still believe it is relevant to the topic of natural selection, because these fish are adapting to help them survive better in the darkness. A question I have is, why exactly do these fish go blind? The researchers suggest that

The purpose of this Betta fish lab was to analyze the behaviors of a male Betta fish when placed in the same bowl as another male and a female, both separate. The reactions and submissiveness/aggressiveness was observed and recorded. For several minutes the two fish were in the same bowl but unable to have contact and observations were recorded. Then, the two fish were allowed to have contact and observations were, again, recorded.

The article “Blind Cave Fish Evolved a Shrunken Brain to Save Energy” talks about a group of fish that got washed into a limestone cave in Mexico many years ago. This fish had to learn how to live in the complete dark and survive with very limited food. The article talks about how the fish slowly lost their eyes and and the portion of the brain that works with the eyes. They explain that this happened so they could conserve energy they needed to survive. They could not use their eyes because it was too dark, so they eventually lost their eyesight then their eyes all together and that portion of their brain. Their taste and smell increased dramatically to be able to survive in this environment. Their taste buds increased and they could sense changes in mechanical pressure. Damian Moran and his colleagues say that they eliminated the circadian rhythm in their metabolism to help conserve more of the energy. Moran collected these fish, their opposites and hybrids of the two fish to do an experiment on in his lab. He

Rheoreaction, which is an inherent behavioural response of fish to swim upstream, underlies fish behaviour in the flow (Fig. 2.1). All other features of behaviour in the stream have to be seen against a background of this particular reation. Rheoreaction has two components of behaviour: orientational and locomotor. Organs of vision, touch, equilibrium (horizontal labyrinth channels) and neuromast help fish find its way against the current. Locomotor activity of fish in the stream can be described by several functional indices: threshold flow rate (its value sets the lower limit of flow rate for fish rheoreaction to develop), critical flow velocity (its value defines the upper limit of velocity interval, within which fish retention in the stream is possible), burst speed and swimming capacity (duration of fish motion at different flow velocities). [1]

In theory catfish are unable to use visual clues to track prey in their dark habitats so they follow recent chemical trails left behind by smaller fish like for instance

In the Gluck lecture the neurobiologist demonstrated how touching the siphon of an Aplysia triggers a withdrawal reflex. The length of time the gill

Transition: After learning about a dolphin’s sense of communication, we can now build upon this information by examining their unique behavior.

Somatosensation is the collective sense of touch which enables us to feel our environment through the specialized receptors in our skin. While in primates, the glabrous hairless skin of the hand palm and fingers serves as sensory organ to palpate objects and obtain tactile information, rodents use their whiskers, organized in a series of rows and columns on the whisker pad located on each side of the snout (Fig.X). Rodent whiskers acquire somatosensory information by their deflection onto objects in the environment, like the digits of the human, they obtain information regarding their shape, texture and location. Somatosensation is an active process involving sensory/motor systems, where in humans a hand will press an object of interest in order to feel its textile features, the rodent macrovibrassae (whisker) will position itself in space, scanning the environment in a series of timed protractions and retractions cycles (5-10Hz). The interruption of the whisking cycle caused by the contact of a whisker onto an object provide the necessary spatio-temporal information for the construction of a sensory percept. A whisker touch contains numerous information carried out by the amplitude of the whisker deflection, the direction, duration, accelation/decelaration on contact, frequency of the contact, force along the axial shaft and resonance frequency of the whisker.

Bottlenose dolphins find fish by using echolocation. This is when a dolphin sends out a beam of short sonar pulses from its melon, or forehead. The beam reflects off of fish or other objects and echoes back to the lower jaw. The echoes are then sent to the ear bones where they are characterized. Using echolocation, dolphins are able to locate prey that is buried up to one and a half feet under the sand (Cahill 140-141).