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Questions and Answers
What is the primary difference between how animals acquire energy and how fungi acquire energy?
What is the primary factor that affects the energy consumption of an animal, leading to a higher metabolic rate?
What is the energy expenditure of an animal at rest, excluding activity and digestion?
What is the primary purpose of hibernation in animals?
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What is the primary reason why penguins have a high energy expenditure?
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What is the primary difference between true hibernators and animals that can wake up quickly during hibernation?
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What is the primary mechanism used by endothermic animals to maintain a steady internal temperature?
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Which of the following is an example of a thermoregulation strategy used by animals?
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What is a key characteristic of ectothermic animals?
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Which of the following animals is an example of an endothermic animal?
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What is the primary function of circulatory adaptations in thermoregulation?
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How do naked mole-rats regulate their body temperature?
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Which animal group is capable of exhibiting both ectothermic and homeothermic characteristics?
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Which physiological adaptation allows walruses to conserve heat in cold environments?
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What is the term for the ability to maintain a constant internal temperature despite changes in the external environment?
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Which behavioral adaptation do birds use to regulate their body temperature?
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Which physiological adaptation is used to generate heat through metabolic processes without shivering?
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What is the primary function of the brain in temperature regulation?
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What type of feedback loop occurs when a product reaches a high level and triggers a response to decrease production?
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What is the primary function of melatonin in regulating sleep-wake cycles?
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What is the primary characteristic of annual rhythms in animals?
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What is the primary function of the internal clock in regulating circadian rhythms?
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What is the term for the specific conditions an animal's body strives to maintain, such as osmolarity and oxygen levels?
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What is the primary function of the nervous system in regulating animal body functions?
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Which system is responsible for regulating body functions through the release of hormones into the bloodstream?
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What is the primary difference between regulators and conformers in terms of their internal environment?
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What is the term for the ability of an animal to maintain a steady internal environment despite changes in the external environment?
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What is the role of the hypothalamus and pituitary glands in the endocrine system?
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What is the primary characteristic of the nervous system in terms of its control of body functions?
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What is the level of organization that is formed by organized organelles?
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What is the primary function of epithelial tissues?
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What is the characteristic that distinguishes skeletal muscle from smooth muscle?
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What is the primary function of glial cells in nervous tissues?
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What is the characteristic that distinguishes cardiac muscle from skeletal muscle?
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What is the level of organization that is formed by organized organ systems?
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Which characteristic is common to both amphibians and amniotes?
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What is the primary function of the allantois in amniotic eggs?
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Which group of tetrapods has the characteristic of producing milk for their young?
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What is the primary function of feathers in birds?
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Which characteristic distinguishes marsupials from placentals?
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What is the primary function of the chorion in amniotic eggs?
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What is the primary characteristic that distinguishes vertebrates from other chordates?
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What is the primary characteristic that distinguishes jawed vertebrates (gnathostomes) from jawless vertebrates?
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What is the primary characteristic of cartilaginous fish (chondrichthyes)?
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What is the primary characteristic of bony fish (osteichthyes)?
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What is the primary characteristic that distinguishes lampreys and hagfish from other vertebrates?
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What is thought to be responsible for the increased complexity of vertebrates?
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What is a characteristic of the notochord in cephalochordates?
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What is the function of the pharyngeal slits in tunicates?
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What is the defense mechanism of tunicates?
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What is unique about the post-anal tail in cephalochordates?
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What is the function of the cilia in the pharynx of tunicates?
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What is the primary characteristic that distinguishes cephalochordates from tunicates?
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What is the main function of the notochord in chordates?
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What is the characteristic of pharyngeal clefts in chordates?
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What is the characteristic of the dorsal hollow nerve cord in chordates?
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What happens to the notochord in more advanced chordates?
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What is the function of the post-anal tail in chordates?
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What is the characteristic of the post-anal tail in humans?
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What is the primary characteristic that distinguishes echinoderms from chordates?
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Which of the following is NOT a characteristic of phylum Chordata?
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What is the primary function of the water vascular system in echinoderms?
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Which of the following is a characteristic of subphylum Cephalochordata?
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What is the primary function of the pharyngeal slits in chordates?
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Which of the following is a characteristic of subphylum Tunicata?
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What is the main characteristic that distinguishes Nematodes from Arthropods?
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What is the primary function of the body cavity in Nematodes?
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What is the process of shedding old skin in Nematodes called?
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How do muscles contribute to locomotion in Nematodes?
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What is the characteristic of Nematodes that allows them to be found in almost every environment?
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What is the primary function of the reproductive organs in Nematodes?
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What is a characteristic that is common to all Lophotrochozoa?
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Which of the following is a characteristic of Platylhelminthes?
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What is a characteristic of Annelids?
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What is a characteristic of Mollusks?
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Which class of Platyhelminthes includes free-living flatworms?
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What is a characteristic of Bilateria?
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Which characteristic is shared by all phyla in the Lophotrochozoa clade?
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What is the function of the mantle in mollusks?
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Which type of annelid has many bristles visible on the lateral sides of the animal?
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What is the primary function of the corona in rotifers?
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Which characteristic is unique to echinoderms?
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What is the primary purpose of the numbing effect secreted by parasitic leeches?
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What is the primary function of choanocytes in sponges?
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What is the main characteristic that distinguishes Class Calcarea from Class Demospongia?
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What is the primary function of the gastrovascular cavity in cnidarians?
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What is the characteristic that distinguishes phylum Ctenophora from phylum Porifera?
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What is the primary function of pinacocytes in sponges?
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What is the primary characteristic that distinguishes Class Hexactinellida from Class Demospongia?
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What is the characteristic that defines the clade Bilateria?
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What is the term for animals where the mouth forms second, with radial cleavage and a coelom forming from pockets in the gut?
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What is the term for multi-cellular organisms?
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What is the term for animals with true tissues?
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What is the term for the sister taxa to the rest of the animals?
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What is the hypothetical ancestor to all animals?
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What characteristic is common to deuterostomes and defines their embryonic development?
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What is the term for the process of molting an old covering of the body, characteristic of ecdysozoans?
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What is the characteristic of lophotrochozoans that is involved in the development of their embryos?
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Which group of animals is the sister taxa to the rest of the animals, according to the molecular phylogenetic tree?
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What is the characteristic of the clade Bilateria, according to the molecular phylogenetic tree?
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What is the ancestor to all animals, according to the molecular phylogenetic tree?
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What is the primary characteristic of Silla mates?
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What is the primary difference between protostomes and deuterostomes?
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Which of the following is a characteristic of protostomes?
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What is the primary difference between a true coelom and a pseudo coelom?
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Which of the following is a characteristic of deuterostomes?
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What is the primary characteristic of Acl mates?
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What is characteristic of animals with two layers of development?
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Which of the following forms a space or coelom in animals with three layers of development?
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What is the term for the cavity that forms when the mesoderm forms a cavity but does not completely surround the internal cavity?
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What is the primary characteristic that distinguishes animals with three layers of development from those with two layers of development?
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Which of the following is an example of an animal with two layers of development?
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What is the term for the layers of embryonic tissue that form during development?
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What is unique to animal cells compared to plant cells?
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What type of tissue provides structural support and protection in animals?
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What is the term for the process in which an animal consumes waste or dead organic matter, recycling nutrients?
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What is the result of gastrulation in embryonic development?
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What is the term for the type of reproduction that involves producing genetically identical offspring?
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What is the unique tissue that allows for movement and locomotion in animals?
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Study Notes
Energy and Animals
- All living organisms require energy to survive, which is obtained through the consumption of food
- Animals acquire energy through ingesting food, which is different from other organisms like fungi that digest their food externally
Bioenergetics
- Bioenergetics is the study of the energy budget of animals, focusing on the energy acquired from food and used for various activities
- Factors affecting energy consumption include body size, activity level, and environment
- Metabolic rate is the amount of energy used per unit of time and can be measured by heat loss, oxygen consumption, or carbon dioxide production
Energy Consumption and Body Size
- Larger animals require more energy overall, but less energy per gram of body mass
- Smaller animals require more energy per gram of body mass due to their larger surface-to-volume ratio, which increases heat loss
- This is why smaller animals often have higher metabolic rates than larger animals
Basal Metabolic Rate (BMR)
- BMR is the energy expenditure at rest, excluding activity and digestion
- BMR is directly proportional to body mass, with larger animals requiring more energy at rest
- Humans have a BMR of around 1600-1800 calories per day for men and 1400-1600 calories per day for women
Energy Allocation
- Animals allocate energy for various activities, including basal metabolism, activity, growth, reproduction, and thermoregulation
- The proportion of energy allocated to each activity varies depending on the species and environment
Energy Conservation Strategies
- Daily torpor: a physiological strategy where an animal reduces its metabolism and body temperature to conserve energy
- Hibernation: a prolonged state of sleep with reduced metabolism, heart rate, and body temperature, lasting weeks or months
Examples of Energy Conservation
- Penguins: high energy expenditure for activity and thermoregulation due to their cold environment
- Mice: high metabolic rate due to their small body size and high surface-to-volume ratio
- Woodchucks: true hibernators, with reduced metabolism and heart rate during hibernation
- Bears: can hibernate, but can also wake up quickly and become active if necessary
Energy and Animals
- All living organisms require energy to survive, obtained through consuming food
- Animals acquire energy by ingesting food, differing from organisms like fungi that digest food externally
Bioenergetics
- Study of energy budget in animals, focusing on energy from food and usage for various activities
- Factors affecting energy consumption: body size, activity level, and environment
- Metabolic rate: amount of energy used per unit of time, measurable by heat loss, oxygen consumption, or carbon dioxide production
Energy Consumption and Body Size
- Larger animals require more energy overall, but less energy per gram of body mass
- Smaller animals require more energy per gram of body mass due to larger surface-to-volume ratio, increasing heat loss
- Smaller animals often have higher metabolic rates than larger animals
Basal Metabolic Rate (BMR)
- Energy expenditure at rest, excluding activity and digestion
- BMR directly proportional to body mass, with larger animals requiring more energy at rest
- Human BMR: around 1600-1800 calories per day for men, 1400-1600 calories per day for women
Energy Allocation
- Animals allocate energy for basal metabolism, activity, growth, reproduction, and thermoregulation
- Proportion of energy allocated to each activity varies depending on species and environment
Energy Conservation Strategies
- Daily torpor: reducing metabolism and body temperature to conserve energy
- Hibernation: prolonged state of sleep with reduced metabolism, heart rate, and body temperature, lasting weeks or months
Examples of Energy Conservation
- Penguins: high energy expenditure for activity and thermoregulation due to cold environment
- Mice: high metabolic rate due to small body size and high surface-to-volume ratio
- Woodchucks: true hibernators with reduced metabolism and heart rate during hibernation
- Bears: can hibernate, but can also quickly wake up and become active if necessary
Thermal Regulation
- Ability to maintain a steady internal temperature despite changes in the external environment
- Two types: endothermy and ectothermy
Endothermy
- Internal mechanisms to generate heat, such as metabolic processes
- Examples: mammals and birds
Ectothermy
- Rely on external sources of heat, such as the sun or a warm rock
- Examples: fish, invertebrates, and reptiles
Thermoregulation Strategies
- Insulation: using fat, feathers, or fur to reduce heat loss
- Circulatory adaptations: counter-current heat exchange, where arteries and veins are situated close together
- Evaporative cooling: losing heat through evaporation of water, such as sweating or panting
- Behavioral responses: changing behavior to regulate temperature, such as seeking shade or burrowing underground
- Metabolic adjustments: increasing metabolism to generate heat, such as shivering or non-shivering thermogenesis
Examples of Thermoregulation
- River otters: maintain a steady body temperature despite changes in water temperature
- Naked mole-rats: allow their body temperature to fluctuate with the temperature of their underground tunnels
- Fish: can be both ectothermic and homeothermic, depending on the environment
- Birds: use feathers for insulation and behavioral adaptations to regulate temperature
- Walruses: use blubber for insulation and behavioral adaptations to regulate temperature
Key Terms
- Homeothermy: maintaining a constant internal temperature despite changes in the environment
- Poikilothermy: allowing internal temperature to fluctuate with the environment
- Counter-current heat exchange: a circulatory adaptation that helps conserve heat
- Vasodilation: expanding blood vessels to release heat
- Vasoconstriction: constricting blood vessels to conserve heat
- Evaporative cooling: losing heat through evaporation of water
- Non-shivering thermogenesis: generating heat through metabolic processes without shivering
Regulation of Animal Body Functions
- Animal bodies are regulated by internal mechanisms to optimize energy use and maintain a stable internal environment.
- Feedback control is a key concept in regulating animal body functions, involving two main systems: nervous and endocrine systems.
Nervous System
- The nervous system regulates body functions through electrical impulses sent by nerve cells (neurons) to specific tissues.
- Neurons have a long extension called an axon, which transmits electrical charges that change from a polarized state to a depolarized state.
- The nervous system provides momentary or on-demand control of body functions.
Endocrine System
- The endocrine system is a set of glands that produce and release hormones, which are signaling chemicals that travel through the bloodstream to reach target cells.
- Hormones are produced by glands that don't have ducts, meaning they are released directly into the bloodstream.
- The endocrine system is often controlled by master glands, such as the hypothalamus and pituitary.
Regulation Strategies
- Regulators are animals that use internal mechanisms to adjust metabolic rates, maintain a steady internal environment, and achieve homeostasis.
- Conformers are animals that allow internal conditions to follow the environment, without regulating their internal environment.
Homeostasis
- Homeostasis is the ability to maintain a steady internal environment despite changes in the external environment.
- Homeostasis is achieved through internal strategies, such as internal organs that help maintain a steady state.
- Set points are specific conditions that an animal's body strives to maintain, such as osmolarity, oxygen levels, and temperature.
Temperature Regulation
- The body maintains a set point temperature of around 37°C (98.6°F) through internal mechanisms, such as sweat production and capillary expansion/contraction.
- The brain serves as a sensor and control center, detecting changes in body temperature and responding with electric impulses to regulate body functions.
Feedback Loops
- Negative feedback loops occur when a product (e.g., hormone) reaches a high level, triggering a response to decrease production.
- Positive feedback loops occur when a product (e.g., hormone) reaches a high level, triggering a response to increase production.
Cyclical Variation
- Cyclical variation is a type of regulation that involves regularly repeating patterns, such as circadian rhythms (daily) and annual rhythms (yearly).
- Circadian rhythms are controlled by the body's internal clock, influencing sleep-wake cycles, feeding, and other activities.
Melatonin and Sleep
- Melatonin is a hormone associated with sleep, with levels increasing at night and decreasing during the day.
- Melatonin levels peak at around 4:00 a.m. and then decrease, leading to increased metabolic activity and wakefulness.
Annual Rhythms
- Annual rhythms are repeating patterns that occur over the course of a year, influencing activities such as reproduction and migration.
- Examples of annual rhythms include seasonal reproduction in animals, where reproduction occurs during specific times of the year when resources are available.
Organization of Life
- Life can be studied at multiple levels of hierarchical organization, including molecules, organelles, cells, tissues, organs, organ systems, and organisms
- Each level of organization exhibits emerging properties, new functions, and new abilities that are not present in the lower levels
Levels of Organization in Animals
- Molecules are the basic building blocks of life
- Organelles are formed by organized molecules
- Cells are formed by organized organelles
- Tissues are formed by organized cells of the same kind
- Organs are formed by organized tissues
- Organ systems are formed by organized organs
- Organisms are formed by organized organ systems
Tissues in Animals
- There are four main types of tissues: epithelial, connective, muscle, and nervous tissues
- Epithelial tissues provide protection, form outer coverings, and line internal cavities
- Connective tissues support and connect other tissues and organs, provide elasticity and strength
- Muscle tissues are unique to animals, providing movement and locomotion
- Nervous tissues are unique to animals, providing sensing and response to stimuli
Epithelial Tissues
- Classified based on cell shape: cuboidal, columnar, and squamous
- Functions include protection, absorption, and secretion
- Found in outer coverings, internal cavities, and lining of organs
Connective Tissues
- Diverse in cell type and function
- Functions include support, connection, and provision of elasticity and strength
- Types include loose, fibrous, bone, cartilage, blood, and adipose tissue
- Cells may be surrounded by an extracellular matrix
Muscle Tissues
- Three types: skeletal, smooth, and cardiac
- Skeletal muscle: striated, multinucleated, and voluntary
- Smooth muscle: non-striated, single nucleated, and involuntary
- Cardiac muscle: striated, single nucleated, and involuntary
- Functions include movement, locomotion, and contraction
Nervous Tissues
- Unique to animals
- Functions include sensing, interpreting, and responding to stimuli
- Types include neurons and glial cells
- Neurons transmit signals, process information, and produce responses
- Glial cells provide maintenance, nourishment, and support to neurons
Tetrapod Diversity and Characteristics
- Tetrapods have four limbs that can be arms or legs, and are characterized by limbs with digits for locomotion away from water.
- They have a neck that allows for separate movement of the head from the rest of the body.
- Their pelvic girdle (pelvic bones) is fused to support the body.
- They lack gills and instead rely on lungs for respiration.
- They have a ribcage that expands for air intake and oxygenation.
Amphibians
- Amphibians are the first group of tetrapods.
- They have moist skin for gas exchange (oxygen intake and CO2 removal).
- They use lungs for respiration, but also breathe through the mouth.
- Their eggs require water for fertilization.
- Examples include frogs, toads, salamanders, and caecilians.
Amniotes
- Amniotes have amniotic eggs with a shell (sometimes flexible, like parchment paper).
- They have impermeable skin to prevent water loss.
- Their embryos develop inside the egg with an allantois (waste storage) and chorion (gas exchange).
- Examples include reptiles, birds, and mammals.
Reptiles
- Reptiles have scales covering their skin.
- They are ectothermic, regulating body temperature using external sources.
- They lay eggs on land.
- Examples include turtles, snakes, lizards, and crocodiles.
Birds
- Birds have hollow, lightweight bones.
- They have feathers for insulation and flight.
- They are endothermic, generating heat internally.
- They lay eggs in nests.
- Examples include various species of birds.
Mammals
- Mammals produce milk for their young using mammary glands.
- They are endothermic, generating heat internally.
- They retain heat using hair or blubber.
- Their brain size is larger in proportion to body size.
- Examples include:
- Monotremes: egg-laying mammals (e.g., platypus, echidna).
- Marsupials: develop in a placenta, but young are born underdeveloped and complete development in a pouch (e.g., kangaroo, koala).
- Placentals (Eutherians): develop fully in the placenta and are born with advanced development (e.g., humans, horses, giraffes).
Vertebrates
- Possess a backbone, which can be made of bony or cartilaginous tissue
- Have greater motility and require a more developed nervous system and sensory organs
- Have a more complex brain and a protective skull and vertebrae that enclose the spinal cord
Characteristics of Vertebrates
- Presence of a backbone (vertebrae) that enclose the spinal cord
- A more elaborate skull that protects the brain
- Better structures for locomotion and sensing the environment
- More developed nervous system and sensory organs
Mixini (Hagfish) and Lampreys
- Most basal group of vertebrates
- Cartilaginous skull and rudimentary vertebrate
- Jawless (agnathans) with a mouth surrounded by sharp tooth-like structures
- Marine animals that live on the ocean floor and are scavengers
- Lampreys are parasitic, attaching to other fish to feed on their blood and fluids
Nathostomes (Jawed Vertebrates)
- Mouth operated by jaws that can open and close
- Jaws developed from gill arches during embryonic development
- More developed central nervous system and protective skull
- Include sharks, bony fish, and tetrapods (amphibians, reptiles, birds, and mammals)
- Duplication of hox genes thought to be responsible for increased complexity
Jawed Fish (Gnathostomes)
- Lateral line canal allows sensing of water currents and direction
- Specialized hair cells detect vibrations in water
- Complete digestive system and cloaca (shared exit for excretory, digestive, and reproductive systems)
Cartilaginous Fish (Chondrichthyes)
- Backbone composed primarily of cartilage
- Include sharks, rays, and skates
- Complex sensory system detects electrical fields and chemicals in water
- Acute sense of smell and detection of blood in water
Bony Fish (Osteichthyes)
- Bony skeleton made of bony connective tissue
- Protective operculum covers the gills
- Paired fins (pectoral, pelvic, dorsal) aid in locomotion
- Swim bladder helps control buoyancy
- Reproduce by releasing eggs or sperm outside their bodies
Invertebrate Chordates
- Lack a backbone and vertebrae but possess the four characteristics of chordates
Cephalochordates (Lancelets)
- Possess a streamlined body with a mouth surrounded by cirri (tentacle-like structures)
- Have a post-anal tail
- Exhibit the four shared traits of chordates:
- Notochord: a flexible, protective rod of cells that provides protection to the dorsal hollow nerve cord
- Dorsal hollow nerve cord
- Pharyngeal pouches that develop into pharyngeal slits, allowing water to pass through and aid in food collection
- Post-anal tail
Characteristics of Cephalochordates
- Notochord remains in the adult as a flexible but supportive structure
Tunicates (Urochordates)
- In the larval stage, possess a notochord that provides protection to the dorsal hollow nerve cord
- In the adult stage, the notochord disappears, leaving no backbone and no notochord
- Retain some characteristics of chordates:
- Pharynx with slits, allowing water to move through and bring food particles
- Pharynx covered with cilia, aiding in guiding suspended food particles towards the esophagus
- Also known as sea squirts due to their ability to squirt a jet of water as a defense mechanism
- Filter feeders: collect water, filter out suspended food particles, and expel excess water through the excurrent siphon
Chordate Characteristics
- Chordates share four synapomorphies: notochord, dorsal hollow nerve cord, pharyngeal clefts, and a post-anal tail.
Notochord
- A flexible rod that runs along the length of a chordate from embryonic development to adult stages.
- Provides protection to the dorsal nerve cord.
- Serves as an attachment site for muscles.
- Remains unchanged from larval to adult stages in less complex chordates (e.g., cephalochordates).
- Replaced by a backbone (vertebrae) in more complex chordates (e.g., vertebrates).
Dorsal Hollow Nerve Cord
- A hollow nerve cord characteristic of all chordates.
- Located dorsally (towards the back).
- Composed of neurons and fluid-filled space.
- Develops into the central nervous system (brain and spinal cord) in more advanced chordates.
Pharyngeal Clefts
- Pouch-like structures that form behind the mouth in chordates.
- Develop into pharyngeal slits in many chordates, allowing for gas exchange and food collection.
- Develop into structures such as the ear, throat, and neck in more advanced chordates.
Post-Anal Tail
- A muscular structure that aids in locomotion and balance.
- Present in most chordates during the adult stages.
- Remnants in humans are the fused vertebrae at the bottom of the backbone (coccyx).
- Important for propulsion and movement underwater in fish.
Deuterostomes
- Deuterostomes are animals where the blastopore becomes the anus and the mouth forms second.
- They encompass two phyla: Echinodermata and Chordata.
Phylum Echinodermata
- Characterized by spiny skin, internal skeleton of calcareous plates, and a unique water vascular system.
- Water vascular system is used for pumping and filling up the two feet for locomotion.
- Radial symmetry in adults, but bilateral symmetry in larvae.
- Examples of echinoderms include:
- Sea stars (Class Asteroidea)
- Sea urchins (Class Echinoidea)
- Brittle stars (Class Ophiuroidea)
- Sea cucumbers (Class Holothuroidea)
- Sea lilies and feather stars (Class Crinoidea)
Phylum Chordata
- Characterized by bilateral symmetry, deuterostomy, and coelomate body.
- Possess a single dorsal nerve cord, notochord, and post-anal tail at least during development.
- Pharyngeal slits are present during embryonic development.
- Subphylum Cephalochordata:
- Includes lancelets (e.g., Amphioxus)
- Retain the notochord throughout their life
- Subphylum Tunicata:
- Includes tunicates (sea squirts)
- Have a notochord during embryonic development, but it disappears in adults
Clade Myriapoda
- Most invertebrates are classified in this clade due to bilateral symmetry.
Nematodes (Roundworms)
- Characterized by bilateral symmetry and non-segmented bodies.
- Found in almost every environment, with an estimated thousands per cubic centimeter of soil.
- Some are parasites of various organisms, including plants and humans.
- Examples: pinworms, heartworms, and hookworms.
Body Structure of Nematodes
- Elongated, thread-like body with a complete digestive system (tube within a tube).
- Body cavity (pseudocoelom) lined by mesoderm and endoderm.
- No exoskeleton; instead, they have a tough cuticle that provides some support.
Reproduction in Nematodes
- Separate sexes with distinct reproductive organs (testes in males, ovaries in females).
- Energy is focused on mating and breeding, with males having multiple testes.
Hydrostatic Skeleton in Nematodes
- Consists of a tough cuticle, muscles, and a fluid-filled body cavity.
- Muscles help constrict the body, creating water pressure for locomotion.
Ecdysis in Nematodes
- Process of shedding old skin (cuticle) and secreting a new one to accommodate growth.
Arthropods
- Characterized by tough exoskeletons, jointed appendages, and segmented bodies.
- Include insects, arachnids, crustaceans, and others.
Body Structure of Arthropods
- Exoskeleton provides protection, support, and attachment points for muscles.
- Jointed appendages allow for flexibility and movement.
- True coelom (body cavity) and an abundance of sensory organs.
Examples of Arthropods
- Arachnids (spiders, scorpions, ticks, and mites).
- Crustaceans (crabs, lobsters, shrimp).
- Insects (butterflies, beetles, flies, wasps, ants).
- Myriapods (centipedes, millipedes).
Molting in Arthropods
- Process of shedding old exoskeleton and secreting a new one to accommodate growth.
- Necessary for arthropods to increase in size.
Classification of Animals
- The majority of animals belong to the clade Bilateria, characterized by bilateral symmetry.
- Bilateria is divided into three main groups: Deuterostomia, Ecdysozoa, and Lophotrochozoa.
Phylum Platyhelminthes
- Platyhelminthes are flatworms characterized by a flattened body shape.
- They have a gastrovascular cavity, which is a single opening for food and waste.
- They have a hydrostatic skeleton, which relies on a tough cuticle, muscle cells, and water pressure.
- Examples of platyhelminthes include free-living flatworms, flukes, and tapeworms.
Classifications of Platyhelminthes
- Class Turbellaria: free-living flatworms, such as planarians.
- Class Monogenea: parasitic flatworms, such as flukes.
- Class Cestoda: parasitic flatworms, such as tapeworms.
Phylum Annelida
- Annelids are segmented worms, such as earthworms and leeches.
- They have a true coelom and a complete digestive system.
- They have a hydrostatic skeleton, which relies on a tough cuticle, muscle cells, and water pressure.
- They have a concentration of sensory organs around the head region.
Phylum Mollusca
- Mollusks are animals with a soft, unsegmented body, often protected by a shell.
- They have a mantle, which is a specialized tissue that secretes the shell.
- They have a muscular foot, which is used for locomotion.
- Examples of mollusks include snails, slugs, clams, and cephalopods.
Phylum Brachiopoda
- Brachiopods are marine animals that have a feeding structure called a lophophore.
- They have a shell, which is secreted by the mantle.
- They are often referred to as "lamp shells."
Phylum Rotifera
- Rotifers are small, aquatic animals that have a feeding structure called a corona.
- They have a complete digestive system and a true coelom.
- They are often referred to as "wheel animals" due to the rotation of their corona.
Phylum Echinodermata
- Echinoderms are marine animals that have a unique body shape, often with five-part symmetry.
- They have a water vascular system, which is used for movement and feeding.
- Examples of echinoderms include starfish, sea urchins, and sea cucumbers.
Asexual Reproduction
- Earthworms can reproduce asexually by cutting them in a specific location, allowing each broken part to grow into a new individual.
- If an earthworm is cut in half and both parts survive, it will result in two worms from one original worm.
Annellid Classes
- Polykitae: have many bristles, visible on the lateral sides of the animal.
- Oligokita: have few bristles, found in earthworms, which can be felt as roughness on the body.
Earthworms
- Earthworms are familiar animals, often used as bait in fishing.
- They have bristles on their body, which can be felt as roughness.
- Some species of earthworms in Australia can grow up to 9 feet in length.
Leeches (Hirudinea)
- Some leeches have no purpose, while others are parasites.
- Parasitic leeches secrete a numbing effect, making it impossible to feel when they attach to the body.
- They use this local anesthetic to suck blood without being detected.
Phylum Porifera (Sponges)
- Basal taxon, diverged earlier from all other animal lineages
- Characterized by pores (ostea) and a large opening (osculum) for water flow
- No tissues, just a grouping of similar cells with specific functions
- Cells are not connected by cellular junctions
Sponges: Cell Types
- Choanocytes: flagellated cells, responsible for food capture and phagocytosis
- Amoebocytes: amoeba-like cells, involved in digestion and distribution of nutrients
- Pinacocytes: flat cells, form the outer layer of the sponge
Sponges: Body Structure
- Spongocele: the main cavity of the sponge where water collects
- Endoskeleton: internal skeleton made of spicules (sharp, spiny objects)
- Spicules can be made of calcium carbonate, silicon dioxide, or protein (spongin)
Classification of Sponges
- Class Calcarea: spicules made of calcium carbonate
- Class Demospongia: spicules made of silicon dioxide or protein
- Class Hexactinellida: spicules made of silicon dioxide, often with six-pointed structures
Phylum Cnidaria
- Radial symmetry, diploblastic (two layers of embryonic tissues: ectoderm and endoderm)
- Body consists of three main layers: ectoderm, mesoglea, and gastrodermis
- Gastrovascular cavity: a cavity for digestion and circulation of nutrients
- Incomplete digestive system: food enters through the mouth, and waste is expelled through the mouth
Cnidarians: Cell Types
- Ectoderm: outer layer of cells, forms the epidermis
- Gastrodermis: inner layer of cells, lines the gastrovascular cavity
- Mesoglea: gelatinous layer between the ectoderm and gastrodermis
Cnidarians: Body Types
- Polyp: cylindrical body type, attached to one place
- Medusa: bell-shaped body type, free-swimming
Classification of Cnidarians
- Class Hydrozoa: includes hydras and obelias
- Class Cubozoa: includes box jellyfish
- Class Anthozoa: includes anemones, corals, and sea fans
- Class Scyphozoa: includes sea jellies
Phylum Ctenophora (Cone Jellies)
- Characterized by eight cones of cilia and biradial symmetry
- Hydrostatic skeleton, gastrovascular cavity, and two main tissue layers
Phylogenetic Trees of Animals
- There are two approaches to constructing animal phylogenetic trees: morphological classification and molecular phylogenetic classification.
Rooted Phylogenetic Tree
- The tree is rooted, meaning it identifies a common ancestor to all animals.
- The hypothetical ancestor is a colonial kawano flagellate, a group of single-cell organisms living in colonies.
Metazoans
- All animals belong to the clade Metazoa, meaning they are multi-cellular organisms.
- The phylum Porifera is considered basal and is a sister taxa to the rest of the animals.
True Tissues
- Animals with true tissues are those where cells have certain features connecting them and allowing them to collaborate.
- Most animals belong to the clade Bilateria due to their bilateral symmetry.
Developmental Trends
- Deuterostomes are animals where the mouth forms second, and they have radial cleavage and a coelom forming from pockets in the gut.
- Protostomes are animals where the mouth forms first, and they have a different developmental pattern.
Phylogenetic Classification
- The clade Pilateria includes animals with three germ layers.
- Molecular phylogenetic classification has rearranged the way animals are classified, with some similarities to the morphological classification.
Molecular Phylogenetic Tree
- The molecular phylogenetic tree still includes the colonial kawano flagellate as the ancestor to all animals.
- The sponges are an out-group, but still a sister taxa to the rest of the animals.
- The clade Bilateria is still present, with the deuterostomes and protostomes being further subdivided.
Deuterostomes
- Deuterostomes are animals where the mouth forms second, and they have radial cleavage and a coelom forming from pockets in the gut.
- They are further subdivided into the Lophotrochozoa and the Echinodermata.
Lophotrochozoa
- Lophotrochozoa are animals that sometimes show a feeding structure known as a trochophore, and they form an embryo or larval stage known as the trochophore.
- They are characterized by the presence of certain genes that control the development of the embryos.
Ecdysozoa
- Ecdysozoa are animals that practice ecdysis, the molting of an old covering of the body.
- They are characterized by the presence of nematodes and arthropods, which molt their exoskeleton as they grow and develop.
Germ Layers and Body Cavity
- Animals with three germ layers (ectoderm, endoderm, and mesoderm) are classified into three groups: Silla mates, pseudo Silla mates, and Acl mates.
- Silla mates have a true coelom, a cavity completely surrounded by mesoderm cells.
- Pseudo Silla mates have a pseudo coelom, a cavity not completely formed by mesoderm cells.
- Acl mates lack a coelom, and the space between ectoderm and endoderm is filled with mesoderm cells.
True Coelom vs. Pseudo Coelom
- A true coelom is a cavity formed and completely surrounded by mesoderm cells.
- A pseudo coelom is a cavity not completely formed by mesoderm cells.
- Only animals with three germ layers are designated as Silla mates, pseudo Silla mates, or Acl mates.
Protostomes and Deuterostomes
- Protostomes and Deuterostomes are subdivisions for animals with a true coelom.
- Protostomes have:
- Mouth forming first from the blastopore
- Spiral cleavage pattern
- Coelom forming by splitting from the blastopore
- Embryos showing terminate development
- Deuterostomes have:
- Anus forming first from the blastopore, and mouth forming later
- Radial cleavage pattern
- Coelom forming from a band of cells that differentiate from the endoderm
- Embryos showing indeterminate development
Protostome Development
- Blastopore becomes the mouth
- Spiral cleavage pattern
- Coelom forms by splitting from the blastopore
- Embryos show terminate development
Deuterostome Development
- Blastopore becomes the anus
- Radial cleavage pattern
- Coelom forms from a band of cells that differentiate from the endoderm
- Embryos show indeterminate development
- Mouth forms from an unnamed opening
- Examples: enterocoels (coelom develops from the gut)
Embryonic Development of Animals
- The blastula is the first stage of embryonic development, characterized by a hollow sphere of cells filled with fluid (blastocoel).
- Cells migrate inside the blastula to form a second layer of embryonic tissue called endoderm.
- The formation of a complete layer of endoderm is characteristic of animals with two layers of development (diploblastic).
Germ Layers
- Germ layers are the layers of embryonic tissue that form during development.
- The three main germ layers are:
- Ectoderm (outer layer)
- Endoderm (inner layer)
- Mesoderm (middle layer, forms between ectoderm and endoderm)
Classification of Animals
- Animals can be classified based on the number of germ layers:
- Sponges: no germ layers
- Cnidarians: two layers (diploblastic)
- Flatworms and higher animals: three layers (triploblastic)
Coelom Formation
- In animals with three layers of development, the mesoderm forms a space or coelom.
- A true coelom forms when the mesoderm completely surrounds the internal cavity.
- Animals with a true coelom include:
- Mollusks
- Arthropods
- Echinoderms
- Chordates
- A pseudo-coelom (or false coelom) forms when the mesoderm forms a cavity but does not completely surround the internal cavity.
- Animals with a pseudo-coelom include:
- Nematodes
- Some other invertebrates
Body Cavities
- In animals with a coelom, the coelom develops into spaces inside the body where organs form and function.
- Examples of body cavities include:
- Thoracic and abdominal cavities in humans
- The diaphragm separates the thoracic and abdominal cavities in humans.
Classification of Animals Based on Coelom Formation
- Animals can be classified based on the type of coelom they have:
- True coelom (e.g. mollusks, arthropods, echinoderms, chordates)
- Pseudo-coelom (e.g. nematodes, some invertebrates)
- Acoelom (e.g. flatworms, no coelom or internal cavity)
Characteristics of Animals
- Animals are heterotrophs, requiring energy from consuming other organisms or organic matter
- They cannot produce their own energy like plants, relying on external sources for survival
Types of Feeders
- Herbivores consume plant material, acting as primary consumers
- Carnivores feed on consumers of plants, possibly consuming other carnivores
- Decomposers break down waste or dead organic matter, recycling nutrients
- Parasites feed on another organism without immediate killing, occurring internally or externally
Animal Tissues
- Muscular tissue enables movement and locomotion
- Nervous tissue facilitates sensory perception and communication
- Connective tissue provides structural support and protection, e.g., bone and cartilage
- Epithelial tissue lines and covers the body's surfaces, including cavities and organs
Animal Cells
- Lack cell walls, allowing for flexibility and movement
- Support is provided by specialized tissues, such as bone, cartilage, and skin
Reproductive Strategies
- Asexual reproduction produces genetically identical offspring, e.g., budding or fragmentation
- Sexual reproduction combines genetic material from two parents, resulting in a fertilized egg (zygote)
Embryonic Development
- Fertilized egg (zygote) undergoes rapid cell division, forming a blastula (hollow sphere of cells)
- Blastula stage is critical in embryonic development, followed by gastrulation (formation of layers)
- Gastrulation results in ectoderm (outer layer) and endoderm (inner layer) formation
- Further development may lead to a third layer, forming a gastrula with three layers
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Description
Learn about how animals acquire energy from food and the factors that affect their energy consumption. Understand the concept of bioenergetics and its significance in the study of animals.
