Zoo BI 2

Question 1

Vertebrate

Answer 1

Animals with an internal backbone or spinal column.
Vertebrates have a well-developed head with an encased nervous system, including a brain and nerve chord encased in a backbone.
They also have a muscular system and a skeleton that supports and protects their internal organs and provides mobility.
With a highly developed nervous system, vertebrates can react very quickly to changes in their surroundings, giving them a competitive edge.
Vertebrates are often larger and have more complex bodies than invertebrates.
The most advanced organisms on Earth.
[Vertebrata is a subphylum of the Chordata phylum]

Question 2

Five classes of vertebrates

Answer 2

Fish (actually multiple fish classes), amphibians, reptiles, birds, and mammals.

Question 3

Where do mammals fall in the taxonomy of organisms?

Answer 3

Mammalia is one of the five (actually more because multiple fish classes) classes in the Vertebrata subphylum.
Kingdom: Animalia; Phylum: Chordata; Subphylum: Vertebrata; Class: Mammalia.
There are three divergent lines (subdivisions) of mammals based on their reproductive strategy: the monotremes (which is its own order), marsupials (infraclass w/multiple orders), and placental mammals (infraclass w/multiple orders).

Question 4

What is the oldest living group of mammals?

Answer 4

Monotremes (order: Monotremata)

Question 5

Monotremes

Answer 5

The oldest living group (order) of mammals.
Lay eggs.
There are only two surviving [families], the platypus (family: Ornithorhynchidae) and 4 species of echidna (family: Tachyglossidae).

Question 6

Marsupials

Answer 6

Infraclass within the Mammalia class.
Mammals whose young are born after a short gestation period, in an immature state.
Females in most marsupial species have pouches (e.g, koala, kangaroo)

Question 7

Placental mammals

Answer 7

Infraclass within the mammalia class.
Have a placenta, which facilitates exchange of nutrients and wastes between the blood of the mother and that of the fetus.

Question 8

Mammals distinguishing characteristics (and name some benefits of the characteristics)

Answer 8

Endothermic, which means they generate their own heat. By generating their own heat mammals are free from depending on the ambient temperature of their surroundings for warmth.
Mammals have hair at some point during their life cycle and hair is unique to mammals; hair provides insulation, concealment, signals to others, defensive functions and a sense of the surroundings.
Give birth to live young (except monotremes).
Mammals must breathe air and do so with their lungs. Aquatic animals come to the surface to breathe and replenish their oxygen.
Mammals have dermal glands which include mammary glands in females. Mammary glands produce milk to feed their young. Thus, female mammals invest a great deal of energy caring for their offspring.

Question 9

The most important characteristic in mammal identification?

Answer 9

Its teeth.

Question 10

Describe mammal teeth (generally; specifics are a separate question)

Answer 10

All mammals have teeth except for monotremes, anteaters and certain whales.
Mammals are heterodonts (means having multiple kinds of teeth; unlike a homodont).
Different kinds of teeth perform different functions such as chewing, crushing, cracking, gnawing, grooming, digging, defending and communicating.
The kind of teeth (shape, size and number) reflect their diet and lifestyle.

Question 11

Name one key way to differentiate mammal species

Answer 11

Comparing teeth shape and quantity

Question 12

Which kinds of teeth do most mammals have? Describe their location and function.

Answer 12

Incisors: in the front of the mouth and used for food gathering. They are designed for biting, cutting and stripping.
Canines: also positioned at the front of the mouth. They are sharp for piercing and are designed for grabbing, piercing and tearing. Predators use their canines to kill their prey.
Molars and premolars (also known as cheek teeth): in the sides of the mouth, vary in shape or size depending on their function. Premolars are used for grinding, crushing, slicing, and shearing, whereas molars are designed to grind and crush vegetation.

Question 13

How does a skull reveal information about animal behavior?

Answer 13

A mammal’s lower jaw articulates directly to the skull.
Skulls provide a framework for the muscles an animal needs for chewing and biting.
In this way, the shape of the skull reveals information about the chewing and biting behavior.

Question 14

Describe some specific aspects of a skull that reveal information about animal behavior

Answer 14

Animals that need stronger biting muscles will develop larger bony attachment ridges for these muscles, such as the sagittal crest along the top of the skull and the zygomatic arches (cheek bones) on the sides.
Predators that tackle large prey often develop a sagittal crest, since it provides attachment space for muscle, which is used to snap the jaws shut (e.g., dog/wolf).
Sagittal crests are often larger in males than in females, because they are associated with larger body size.
Herbivorous animals that do a lot of chewing to help break down the cellulose, have a larger muscle attachment sight on the lower jawbone (e.g., cow). If this attachment area is small, chewing is not a necessity such as in a cat or dog.

Question 15

Which animals have hair/fur?

Answer 15

Mammals are the only animals that have hair or fur.

Question 16

What is a pelt?

Answer 16

A mammal’s skin and fur (all still attached).

Question 17

Name some functions of mammal skin

Answer 17

Primary function is defense against injury.
Barrier to protect the animal’s soft inner structures and maintain the internal environment by retaining body fluids.
[Prevent moisture loss.]
[Keep germs out.]
The skin may be extremely tough and durable.

Question 18

Types/functions of fur:

Answer 18

The fur (pelage) is made up of two layers of hair:
-1. dense and soft undercoat - traps a layer of air, providing insulation)
-2. long, coarse hairs form outer coat - protection against wear, can be fluffed up to improve insulation or as defensive/aggressive behavior to make mammal appear larger.
Other functions:
-May also provide insulation against heat (camel, kangaroo or lion). Paler fur reflects the sun’s rays.
-Coloration for camouflage
-Sometimes this coloring is disruptive by patterns of stripes or colors that stand out from the basic background fur color. These patterns allow the animal to blend in with the background mixture of sunlight and vegetation. Body shapes and outlines are not as readily distinguished when animals have disruptive coloration patterns.
-Nerve endings are wrapped around the follicle and are sensitive to a hair’s movement. Mammals use this sense to detect direct physical contact and to gauge wind or water currents.

Question 19

What is hair/fur made of?

Answer 19

Hair/fur is dead and made of keratin.

Question 20

Describe early mammals; when did mammals emerge?

Answer 20

-Mammal ancestors were mammal-like reptiles that were around about the same time as the emergence of dinosaurs.
Early mammals:
-The earliest identifiable mammals were tiny, shrew-like mammals
-Emerged during the late Triassic period about 200 million years ago.
-Probably nocturnal in order to avoid competition with the dominant carnivorous dinosaurs.
-Probably mostly ate insects and lived in the trees.
-Probably laid eggs.
-Superior sense of smell and hearing, backed up by a larger brain, facilitated entry into nocturnal niches with less exposure to dinosaur predation. The nocturnal lifestyle may have contributed greatly to the development of mammalian traits such as being endothermic and having hair.

Question 21

Describe the important factors/events involved in the expansion of mammals

Answer 21

-After the extinction of the Dinosaurs, about 65.5 mya, the Cenozoic became the “Age of Mammals”
-Flowering plants and mammals underwent rapid diversification at this time and filled in open niches that were left vacant by the dinosaurs and marine reptiles
-Mammals took advantage of the new abundant food sources from the evolving flowering plants.
-Part of the successful strategy was the differentiated teeth (incisors, canines, molars), allowing them to adapt to a variety of diets and environments. (Fish, amphibians and reptiles, which all evolved prior to the mammals, had a single tooth morphology.)

Question 22

What is a keystone species? Give an example.

Answer 22

-A species which has a disproportionately large effect on its natural environment relative to its abundance.
-Often a keystone species is a top predator.
-Many mammals have become keystone species
-Example: Wolf. By regulating prey populations, wolves enable many other species of plants and animals to flourish. In this regard, wolves initiate a domino effect – “touching” songbirds, beaver, fish, and butterflies.

Question 23

Name some factors that allow mammals to adapt to and thrive in diverse environments/niches

Answer 23

-Endothermic (don’t have to rely on environment to regulate temp)
-Heterodonts (different kinds of teeth help adapt to different food sources)
-Fur allows for environmental adaptation (help keep warm, help keep cool, camouflage, protection)