Bellringer Flashcards
In your examination of hagfish, you learned they are isosmotic. What does isosmotic mean? How does this apply to hagfish?
Being isomotic refers to having the same osmotic pressure as the surrounding environment. Hagfish are considered isomotic because they can regulate their internal osmolality to match that of their seawater habitat.
Based on your examination of the Amphioxus and the Ammocoetes larvae, how do they compare and contrast?
The key difference I observed is that Amphioxus possess pharyngeal gill slits, which are used to filter food particles from the water, whereas Ammocoetes have gill slits, primarily adapted for respiration in water. Amphioxus appears to have only a single eye, known as the frontal eye, while Ammocoetes possess two lateral eyes located on the sides of their head.
What is the function of claspers on sharks?
Male sharks possess a set of pelvic claspers, which are specialized pelvic fins designed to deliver sperm inside of a female shark.
During the lab you examined a platypus, an example of a monotreme. How do monotremes differ in reproductive strategy from eutherian mammals (like humans)?
Monotremes lay numerous eggs, with offspring hatching at a very immature stage before nursing. In contrast, eutherian mammals have a well-developed placenta and give birth to live young, which possess brown adipose tissue, a specialized organ that helps generate heat.
Some of the key characteristics of mammals relate to reproductive strategies, namely internal fetal incubation and post-natal dependence on the mother by lactation. What advantage is there to the offspring to have extended post-natal care?
Extended post-natal care offers several advantages to offspring, including increased survival through protection from predators and proper nourishment, as well as better development, which enables them to thrive more independently as they grow.
Birds come in many forms and not all are capable of flight. Recall the specimens in the lab, where you saw examples of different birds. Birds particularly vary in length of legs and necks, and shapes of beaks. Provide at least 2 reasons why bird morphology varies so much.
a. The shape of a bird’s bill is often linked to its diet and overall fitness. These variations in shape and size can adapt in response to changes in the environment and habitat. b. Feathers comes in various types, each specialized for different biological roles such as thermoregulation, flight, camouflage, and more. Feather diversification arises from changes in habitat, climate, and behaviour.
While examining the specimens from Class Aves, you read that the uropygial gland is on the dorsal side on the base of the tail. What is the uropygial gland used for?
The uropygial gland secretes oil that waterproofs the feathers and contains antibacterial and antifungal properties, helping to maintain the health of the skin.
What disadvantage does a ground-hugging body form confer in mobility?
The ground-hugging body structure of reptiles can make it difficult to navigate uneven terrain or climb, restricting their range of movement. Additionally, their vestigial legs may reduce speed and agility, which could be a disadvantage of evading predators.
In your examination of the specimens representing Class Reptilia, you were asked to note in general that ground-hugging body forms are typical in this Class. Why is the ground-hugging body form considered an ancestral characteristic?
The ground-hugging body form reflects the early evolutionary adaptations of reptiles to terrestrial environments. This structure is commonly seen in reptiles’ ancient ancestors, which adapted to ground-dwelling for better mobility and heat regulation.
Based on its morphology, in what kind of environment might the Amphiuma be found? Why do you think that environment is correct?
Since Amphiuma lack functional legs, they likely live in aquatic environments. Their lungs are ventilated through air, suggesting they inhabit shallow ponds or swamps.
In your examination of the North American “congo eel”, Amphiuma, you were asked to notice the vestigial legs. What does vestigial mean?
Vestigial structures are ancestral traits that have lost their original function. In Amphiuma, the legs inherited from their ancestors are no longer used for any specific purpose.
Lungfish can estivate. What does estivate mean?
During estivation, organisms conserve energy by reducing activity, slowing their breathing and heart rate, and lowering metabolism to minimize energy use and prevent dehydration.
In the lab, you were asked to notice the counter-shading (darker backside than belly) on the fish. Why do many animals, such as these aquatic species, have counter-shading?
The dark dorsal side of fish provides camouflage by helping them blend in with the water below if they are being viewed from above. This adaptation reduces predation and increases the chances of survival.
In your examination of the Chimaera, you learned that the fleshy operculum in the Chimaera is not homologous with the bony operculum of bony fishes. What does homologous mean?
Homologous structures share a similar evolutionary path, even if they serve different functions. Since the fleshy operculum in the Chimaera is not homologous with the bony operculum of bony fishes, they do not share a common evolutionary origin.
One of the several key features distinguishing sharks and rays from other fish is that their skeletons are made of cartilage and not bone. a. What advantage would this confer?
b. What disadvantage would this confer?
a. Cartilage is less dense than bone, allowing sharks to move quickly through the water, while expending less energy compared to bony fish. b. A bony skeleton provides a greater number of attachment points for the muscle, improving the fish’s swimming efficiency and power.
Note the shape of the exoccipital (= occipital condyle) at the back of the chondrocranium of each specimen you examine. How does the occipital condyle of both the mudpuppy (0.5) and frog (0.5) compare to the fish?
The occipital condyle forms the joint between the skull and vertebral column. In amphibians, such as frogs and mudpuppies, the occipital condyle is divided into a pair of rounded structures, each with an articular surface on either side. In contrast, fish possess a single, flattened articular surface where the skull connects to the vertebral column.
Compare the lizard, alligator and snake skulls with the model of the Tuatara (Sphenodon; a Rynchocephalian). How many temporal fenestra(e) are found in each species? Lizard; Alligator; Snake; Tuatara
Lizard: 2 - diapsid Alligator: 2 - diapsid Snake: 2 - diapsid Tuatara: 2 - diapsid
Why might birds have lost teeth?
This lack of teeth was thought to be an adaptation that facilitated easier prey capture (worms, insects, and vertebrates) and seed consumption. These characteristics played a role in the eventual success of birds.
How does the shape of the mammalian skull compare to the ancestral vertebrates? Think about how mammals move and use their skulls and look for evidence of these differences on their skulls when answering this question.
Several key distinctions emerge when comparing mammalian skulls and movement to those of ancestral vertebrates, highlighting the evolutionary adaptations of mammals. Mammals possess a bony secondary palate that separates the nasal and oral cavities, enabling them to breathe while chewing – a feature absent in ancestral vertebrates, which made simultaneous breathing and feeding difficult. In terms of locomotion, mammals exhibit advanced adaptations, including a flexible vertebral column for efficient movement, limbs positioned under the body to enhance endurance and agility, and paired occipital condyles that allow precise head movements. In contrast, ancestral vertebrates relied on lateral undulation (side-to-side body and tail movements for propulsion), had splayed limbs that made movement less energy-efficient and limited speed, and a less flexible spine that depended more on body bending for locomotion.
Why are the types of teeth shaped the way they are (remember: relate form and function)? List each type along with the reasons for which they have their shape. Incisor; Canine; Premolar and Molar
Incisor: Incisors are flat, chisel-shaped teeth with sharp cutting edges, positioned at the front of the mouth and anchored firmly into the jawbone by a single root. Their primary function is to slice and bite into food, cutting it into manageable pieces. In some mammals, incisors also serve secondary roles, such as grooming fur or other body surfaces. In certain species, specialized incisors are adapted for additional purposes, including defense, digging, or social display. Canine: Canines are pointed, conical teeth with a sharp tip designed for piercing, located next to the incisors. Their long, single roots provide stability to withstand strong forces. Canines are specialized for gripping, puncturing, and holding onto prey. In many species, enlarged canines are used for protection, fighting, and establishing dominance, while in others, prominent canines serve as visual signals for intimidation. Premolar and Molar: Premolars are broad, flat teeth with two or more cusps on the chewing surface, typically having a single root, though some species may have more. Positioned between the sharper canines and flatter molars, premolars help transition from biting to grinding. Molars, located at the back of the mouth, are large, flat teeth with multiple cusps designed for grinding and crushing. They have multiple roots, often two or three, providing added stability. The broad surfaces and multiple cusps of molars make them highly effective at breaking down food into fine particles for swallowing and digestion, contributing to the final stage of food breakdown, enabling mammals to extract the maximum amount of nutrients from their food.
Why is the mobility of the head independent of the vertebral column such an advantage?
The independent mobility of the head from the vertebral column is advantageous because it allows for greater flexibility and efficiency in sensory perception and environmental awareness. Since most animals, including humans, have key sensory organs like the eyes, ears, and nose located in the cranium, being able to move the head without moving the entire body enables quick adjustments. This is particularly useful for navigating surroundings without expending unnecessary energy.
While in the lab, you were instructed to examine the vertebrae of the skeletons on display to see how the vertebrae articulate and to consider the type of motion each vertebral region allows. You were to notice that in some regions, various bones are fused together, while in others, how they either allow movement or prevent it.
Which specimen did you examine?
a. Which is the most flexible vertebral regions?
b. Why did you choose that region?
c. Which regions tend to be less flexible?
d. Why did you choose that region?
a. Cervical vertebrae (Neck) b. Alike to humans, the flexibility of the neck is essential for a dog to quickly scan surroundings and interact with the environment. c. Thoracic vertebrae d. The thoracic vertebrae is the largest region of the spine and connects to the ribcage. The ribcage needs to be stable and supported because its structure protects vital organs like the heart and lungs.
In the lab, you were instructed to look again at the bony fish skeleton: the pelvic girdles of fish do not articulate with the vertebral column. Based on what you have learned about girdles, suggest a possible reason why.
The pelvic girdle in fish is usually embedded in muscle and not fused to the spine to allow for greater mobility. The detached pelvic girdle allows for more flexibility and agility in the fish’s body.
Describe the basic form of the mudpuppies’ pectoral and pelvic girdles (we do not need to know all the parts): How do the limbs relate to the axial skeleton (relative position, size of bones, etc.). (2)
The mudpuppy’s limbs are positioned laterally, meaning they extend out to the sides of the body rather than being positioned directly underneath it as seen in mammals. The limbs are relatively short with the elbows and knees bending at sharp angles.
You examined the frog skeleton in the lab. It has a bony skeleton that differs substantially from the mudpuppy. What differences are there between the frog and mudpuppy when examining the appendicular bones and pelvic girdles?
The structure of the appendages and pelvic girdles in frogs and mudpuppies differ from each other. Frogs have elongated and fused limb bones, while mudpuppies have shorter, more flexible limbs. Additionally, frogs possess a strong, fully ossified pelvic girdle, whereas mudpuppies have a more flexible, cartilaginous pelvic girdle.
How does the basic form of the mudpuppy’s pectoral and pelvic girdle relate to its habitat and mode of locomotion?
Mudpuppies are fully aquatic amphibians that inhabit rivers, streams, and ponds. Their lateral limbs and flat bodies help them stay close to the ground, allowing for efficient movement along the bottom of the terrain. When moving through open water, mudpuppies take advantage of their longer bodies and move similarly to a snake through water, using their tail to push them forward.
Why would these differences exist? Consider modes of locomotion and primary habitat.
Frogs have long, ossified hindlimbs adapted for jumping, providing strength and powerful propulsion. Their shorter forelimbs help with landing and stability. In contrast, mudpuppies have shorter limbs suited for slow crawling along the bottom of aquatic environments. The frog’s pelvic girdle offers a solid base for the muscles needed for jumping, while the mudpuppy’s cartilaginous pelvic girdle allows for greater flexibility.
You examined the snake skeleton in the lab. Snakes are obviously unique in their relatively simple skeletal forms. Identify 2 key different features of the snake postcranial skeleton relative to other tetrapods.
Snakes have completely lost their limbs, unlike other tetrapods, which enables them to move by slithering on the ground. Snakes also possess a longer and more flexible spine, with a significantly higher number of vertebrae than tetrapods, allowing for enhanced flexibility during locomotion.
You examined the turtle skeleton. The turtle is another example of a highly modified, special skeleton. List 1 vertebral and 1 rib modification turtles have relative to other tetrapods.
Turtles have fused vertebrae in the thoracic and pelvic regions. Unlike most tetrapods, the turtle’s thoracic vertebrae are fused to the shell, offering structural support and protection. Additionally, turtles have expanded and fused ribs that are incorporated into the upper part of the shell, providing an additional layer of defense and support.
How do the pelvic and pectoral girdles of the bird differ from the mudpuppy and cat girdles relative to their functions? (2) Pelvic:
Pectoral:
Pelvic: The bird pelvic girdle is adapted for flight by being lightweight and rigid, providing support during flight and bipedal locomotion. The mudpuppy pelvic girdle is cartilaginous and flexible, allowing for lateral movement and crawling in aquatic environments. The cat pelvic girdle is muscular and flexible, designed for running and jumping on land.
Pectoral: The bird pectoral girdle is designed to support the flight muscles, with the scapula allowing for extensive wing movement and effective flight mechanics. The pectoral girdle of mudpuppies is more rigid and supports swimming and crawling in water. The cat’s pectoral girdle is highly flexible and muscular, adapted for terrestrial movement. Since the girdle is not fused to the spine, it allows for a wide range of shoulder and limb movements essential for walking, climbing, and hunting.
You examined the whole cat skeleton and the whole human skeleton. How does the cat form compare to the human? Identify 3 structural differences and consider the function of these differences in terms of motility
The human spine is more rigid with a distinct curvature to aid in upright posture and bipedal walking. In contrast, the cat’s spine is more flexible, which supports running and climbing. The cat’s pelvic girdle is also more flexible, allowing for greater hindlimb movement, while the human pelvis is adapted for walking and standing upright, providing a solid base for the legs. Regarding limbs, cats have very similarly sized forelimbs and hindlimbs relative to their body size, which is suited for quadrupedal movement, whereas humans have longer hindlimbs relative to their body, adapted for bipedal locomotion.
How does the pelvis of the opossum compare to the pelvis of a cat?
The opossum’s pelvis is wider and more flexible, helping with climbing and grasping. It is specialized for generalized movements rather than high-speed running. In contrast, the cat’s pelvis is narrower and more rigid, designed to support fast running. The cat’s pelvis allows for powerful hindlimb movements, suited to its terrestrial life.
Compare the bat wing with that of a bird.
Are the wings of the two groups derived from different bones? (1) Are the limbs homologous or analogous? (1) Are the wings homologous or analogous?
The limbs of bats and birds are composed of the same bones, indicating that they share a homologous origin, meaning that they evolved from a common ancestor. In contrast, although bat and bird wings appear similar in function and form, they are not analogous because they evolved independently in response to similar environmental pressures, not from a common ancestor. The limbs are homologous. The wings are analogous.
