Week 6 Animal Diversity and Animal Form/function
Porifera Anatomy
- Skeleton is composed of collagen and spicules (microscopic spines) - Spicules may be composed of calcium carbonate, silica, or spongin -They lack "True" tissues (characteristics of other animals)
Four types of tissues
1) Epithelial: sheets of cells that cover the outside of the body and line organs and cavities inside the body 2) Connective: spare cells embedded in extracellular matrix; binds and supports other tissues e.g. loose or fibrous connective tissue, cartilage, bone, adipose tissue and blood 3) Muscle: filaments of actin and myosin, which work together to enable contractions; responsible for nearly all types of body movement Nervous: receive, process and transmit information
The benefits of more complex body plans
1) External skeleton protects 2) Sensory organs provide detailed information about environment 3) Internal digestive organs digest food gradually, controlling energy storage 4) Maintaining the body's internal environment allows living in a variable environment
Mollusca types
1) Gastropods (75%): Most have a single shell, found in marine, freshwater or on land and includes snails and slugs 2) Bivalves: Shell in two halves an are sedentary suspension feeders and includes oysters and clams 3) Cephalopods: Internal "shell", modified foot -> siphon, predator includes octopi and squids
Lifestyle of frogs
1) Larval stage: an aquatic herbivore tadpole which initially has gills, tail, and no legs 2) Metamorphosis: Loses tail and develops legs and eardrums. Most species lose gills and develop lungs and modify digestive system to carnivorous diest 3) Adult: a land-based hunter which most skin to improve gas exchange
Heirarchical Organisation of Life (1 is smallest and 9 is the biggest)
1) Molecule 2) Organelle 3) Cell 4) Tissue 5) Organ 6) Organ System 7) Organism 8) Population 9) Ecosystem
Major mammalian clades
1) Monotremes: Includes animals that lay eggs like the echidna, platypus. Found in Australia/PNG 2) Marsupials: Animals where embryone starts to develop in uterus and finishes in a pouch, like possums, kangaroos ans koalas. Found in Australia/ US 3) Placental mammals (eutherians): more complex placenta (organ that feeds embryo) and completes embryonic development within the uterus
Three fundamental challenges of all animals
1) Obtain nutrients and oxygen 2) Fight off infection 3) Produce offsprings Animals can use different strategies to tackle these challenges. Natural selection favours adaptations that increase relative fitness which explains the vast diversity of life. Physical law of nature constrain the range of animal forms
Potential causes of the Cambrian explosion
1) Predator vs pre arms race 2) Response to increase in atmospheric O2 3) Development of Hox genes and microRNA
Types of echinoderms
1) Sea stars: organisms with arms radiating from a central disk and everts its stomach into shell of prey and digests it there and the brings it back inside. Sea starts have considerable regenerative powers and can regrow lost arms. (Members from one genus can even regrow an entire body from a single arm) 2) Brittle stars: organism with a central disks and long flexible arms 3) Sea urchin: organism with rough sperical spines, no arms but 5 rows of tube feet 4) Sea cucumbers: Looks quite different with 5 rows of tube feet
Condrichthyes
1) Sharks: biggest vertebrate predators in the oceans, some suspension feeders but most are carnivores with good sensory systems (vision, smell, sounds and electric field) 2) Ray and skates: Flat bottom-dwelling and eat molluscs 3) Chimaeras: Live in deeper water and feed on shrimps, molluscs and sea urchins
Classes of Osteichthyes
1)Actinopterygii (ray-finned fish): over 27 000 species 2)Sarcopterygii (lobe-finned fish): 2 species of actinista (coelocanths) and 6 species of dipnoi (lungfish)
Invertebrate chordates
2 chordate classes dont have vertebrae: 1) Cephalochordata (lancelets): filter feeders that are relatively rare (but in high density when found) and are up to 6cm in length 2) Urochordata (tunicates): Chordate characteristics apparent in larva and like cephalochordata they are filter feeders. Settles on substrate and then undergoes rapid metamorphosis
Orders of Class Mammalia
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Primary animal "body plans"
A body plan is a particular set of morphological and developmental traits of living organisms. The main features of body pans as they developed throughout the evolution of animals are: 1) Development of true tissues 2) Development of bilateral symmetry 3) Protostome vs deuterostome development Body plans relflect evolution and can help buil anima phylogenetic tree
Eumetazoa
A clade of animals with true tissues
Osteichthyes
A class of fish having a endoskeleton composed of bone in addition to cartilage. Breathe by passing water over gills (in mouth, through pharynx and out operculum). They maintain buoyancy with air-filled sac (swim bladder), which developed from lungs
Notochord
A flexible rod that sits below the nerve cord and provides skeletal support (replaced by bones (vertebral column) in vertebrates)
Amniotes
A member of a clade of tetrapods that have an amniotic egg containing specialized membranes that protect the embryo; mammals, birds+reptiles. More efficient ventilation of lungs and dont breathe through less permeable skin to conserve water
Development of true tissues (1)
A tissue is a callection of cells that act as a functional unit and deliver a specialised function. In most animals, embryon become layered during early deveipment
The Cambrian explosion
About 530 million years ago there was a huge diversity in the early Cambrian era. Fossils from the time included about 50% of all living animal phlya especially bilaterians. This also coincided with a decrease in Ediacarian life forms
Mollusc Anatomy
All have a similar body plan which includes a muscular foot for movement, a visceral mass with most of the organs and a mantle which drapes over the visceral mass and secretes the shell
Chordates
An animal phylum that has a notochord, a dorsal hollow nerve cord, gill (pharyngeal) slits or clefts and post-anal tail at some time in its life cycle
gastrula
An embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm.
Animal phylogeny
Animal phylogenetic tree is based on the similarities in DNA sequence, morphology and body plan
Exchange within the environment
Animals must exchange nutrients, waste products and gases -> further limitation on body size and shape. Rate of exchange is proportional to surface area, while amount of material that needs to be exchanged depends on volume. There are two approaches to tackle this: 1) Optimise body shape 2) Develop specialised exchange surfaces and a circulatory system
Metazoan
Any of a group (Metazoa) that comprises all animals having the body composed of cells differentiated into tissues and organs and usually a digestive cavity lined with specialized cells.
Thermoregulation by behaviour
Basking in the sun, or seeking out the shade in ectotherms. Ectothermy consumes much less energy than endothermy!
bilateral symmetry
Body plan in which only a single, imaginary line can divide the body into two equal halves.
Endocrine vs Nervous
Both differ in signal type, transmission, speed and duration. Endocrine brings on a gradual change that affects the whole body, such as growth, development, reproduction, metabolsim and digestion. Nervous creates immediate and rapid responses to environment, such as reflexes and movement
Ectoprocts
Colonies look like clumps of moss
Insects
Common in terrestrial, freshwater and air. Explosion of species diversity between 359-251 MYA, likely due to a combination of response and co-evolution with new plant speies (gymnosperms and angiosperms) and the evolution of flight.
Amniotic egg
Contains amniotic fluid surrounded by a hard shell which leads to slow dehydration
The great barrier reef
Coral polyps secrete a hard exoskeleton of calciumcarbonate and form symbiosis with algae
Diversity in modern animals
Currently there are over 35 phyla and all but 1 are invertebrates and about half are exclusively marine
Cnidaria
Diverse range of sessile and motil forms including hydra, sea anemone, coral and jellyfish. They have a simple diploblastic radial body plan with not centralised brainn but have nerves associated with sensing
Diploblastic
Early animals have two layer (diploblastic) which consists of ectoderm and endoderm
The development of bilateral symmetry (2)
Early life forms with tissues have radial symmetry (one axis of orietation: top and bottom.) Later organisms dveloped bilateral symmetry (multiple axises of orientation: dorsal vs ventral, left vs right, anterior vs posterior
Ecdysova vs Lophotrochozoa (4)
Ecdysozoans have the ability to shed their exoskeleton several times throughout their life span, whereas lophotrochozoan are the animals who possess a trochophore larvae and a feeding structure called lophophore
Energy requirements
Energy flow and transformation in an animal is called bioenergetics. It determines nutritional needs, and is related to size, activity and the environment. Remember that animals are heterotrophs and harvest their chemical energy from food to produce ATP, which is the used to fuel metabolism and activity.
Humans
Evolved from primates 2.4 MYA with the appearance of Homo sapiens 0.2 MYA. Domain Eukarya Kingdom Animalia (Superphylum deuterostomia) Phylum Chordata (Subphylum Vertebrata) Class Mammalia Order Primate Family Hominidae Genus Homo, Species H. sapiens
Muscular post-anail tail
Extends posterior to anus and is muscular to provide movement. Often greatly reduced during embryonic development
Current animal phylogeny
Four distinct points of division: 1) True tissue 2) Bilateral Symmetry 3) Deuterostome vs protostome 4) Ecdysozoa vs Lophotrochozoa
Platyhelminths (flatworms)
Free-living like planarians or parasitic like a tapeworm
Echinoderms (echinos=spiky and derma-skin)
Generally slow-moving or sessile animals that appear radially symmetrical but larvae are bilateral and adults are off-centres. Endoskeleton is made of hard calcareous plates and they have a unique water vascular system. There are separate male and female individuals.
Birds
Highly diversified (10 000 species) and evolved from dinosaurs 160 million years ago. Anatomical adaptations to flight: 1) Weight saving since no bladder or teeth and honeycombed bones 2) Wings (remodelled tetrapod forelimb) that are aerodynamic 3) Feathers made of beta-keratin 4) Acute vision 5) Fine muscle control
homeostatic regulation
Homeostasis can involve a variety of process e.g. control of internal temperature ("thermoregulation") involves form, function or behaviour
Thermoregulation by form
Insulation (e.g. feathers, fur, blubber), circulatory adaptations (e.g. countercurrent heat exchanger) and brown fat
Arthropod exoskeleton
It is made up of protein and polysaccharide (chitin) and has main advantages: helps avoid water loss (facilitate land dwellers), defense against predators and provides a point of attachment for muscles. One major drawback is molting (ecdysis) which must be done to facilitate growth but is energetically expensive and renders newly molted animals temporarily vulnerable
Myxini (hagfishes)
Jawless marine vertebrates with reduced vertebrae; have head that includes a cartilage skull and brain, eyes, and other sensory organs. They are scavengers with teeth made of keratin.
Petromyxontida (lampreys)
Jawless vertebrates with a skeleton made out of cartilage and are mostly parasites. Larvae life in freshwater streams, then migrate into seas as adults
Triploblastic
Later animals have three layers which consist of the ectoderm, mesoderm and endoderm
Organs
Made up of multiple tissues
Deuterostomia
Main shared features include bilateral symmetry, triploblastic (i.e. including mesoderm) and deuterostome development. Two main phyla (based on DNA analysis not appearance) is echinoderms (sea stars, sea urchins) and chordates (mostly vertebrates)
Bilaterians
Member of a clade of animals with bilateral symmetry and three germ layers.
Bilateria
Members of the branch of eumetazoans possessing bilateral symmetry.
Radiata
Members of the radially symmetrical animal phyla, including cnidarians.
Segemented worms
Mobile or sedentary (<1mm to >3m)
When did animal appear
Molecular clocks and biochemical fossil records suggest that a common ancestor to all animal species lives about 770 million YA. Animals as sponges (i.e. soft-bodied animals like molluscs and cnidrians (sea anenome)) appeared about 700 million YA with evidenc of predation and lasted for about 150 million years.
exchange surfaces
Most animals have surfaces that are specialised for exchanging chemicals with the surroundings. These exchange surfaces are usually internal but are connected to the environment via openings on the body surface (the mouth, for example). The exchange surfaces are finely branched of folded, giving them a very large area. The digestive, respiratory and excretory systems all have such exchange surfaces. The circulatory surfaces carries chemicals transported across these surfaces throughout the body.
Difference in embryonic development 3)
Most tripoblastic animals have a body cavity (coelom) which is a fluid or air-filled space between the digestive tract and outer body wall which has many functions including to cushion suspended organs, allows internal organs to move independently of the outer wall and in soft-bodied organisms, non-compressible fluid can act like a skeleton against which muscles can act like a skeleton which muscles can work against
Lophotrochozoa
Name refers to 2 features observed in some animals in this clade: 1) Lophophore: crown of tentacles for feeding 2) Trochophone larvae: free-swimming larval stage. Includes platyhelmiths, syndermata, ectoprocts, lamp shells, molluscs and segmented worms
Nervous System
Neurons transmit signals (nerve impulses) along dedicated routes (axons) to specific locations and can act on other neurons, muscle cells, cells and glands that produce secretions. Nerve impulses travels long distance along axon as change in voltage (electrical signal) ad shorter inter-cell distance as chemical signal (neurotransmitter). Extremely fact communication and effect only lasts a fraction of a second
Arthropods
One of the most successful animal phyla with more than 1 million species described, mostly insects. They are found in nearly all habitats of the biosphere and there are an estimated 10^18 arthropods living on earth. Includes chelicerates (scorpions), myriapods (millipedes), crustaceans and insects
Organ system
Organs that work together make up an organ system
The major animal phyla
Profiera, Cnidaria, Lyphotrochozoa, Ecdysozoa and Deuterostomia
Syndermata
Recently established and includes rotifers (microscopic multicellular animals with complex organs) and parasitic taxa
Fusiform shape
Rounded, bullet shape where both ends of the fish taper to a point. (ex. sharks, marlins, swordfish, and tuna) used for fast movement e.g. hunting and evading predators
feedback control
Sensor senses changes to the environment, sends the information to the control centre and compares it to the homeostatic state and then the control centre sends information to an effector to respond
Class mammalia
Shared features include nourishing their young with milk, hair and layer of fat under the skin to retain the heat (like birds, mammals are endothermic) and differentiated teeth to chew different foods. First true mammals emerged in the Jurassic era (200-145 MYA) and coexisted with dinosaurs but were small and not particularly abundant. Adaptive radiation after extinction of large dinosaurs (65-60 MYA)
Endocrine systems
Signal molecules (hormones) are released into the blood stream and carried to all locations in the body. Only cells that have receptors for that specific hormone respond e.g. Thyroid Stimulating Hormone (TSH) acts only on thyroid gland, but thyroid gland then produces Thyroid Horomone, which acts on almost every cell of the body (increases bodily functions like oxygen consumption and heat production). Hormones remain the blood for minutes to hours i.e. long-lasting effect.
Cnidocytes
Since cnidocytes are predators they use tentacles to capture prey. Specialised cells called cnidocytes throw nematocysts (similar to harpoons) e.g. box jellyfish
Major organ systems
Skeletal: bones and joints Muscular: muscles (who'd a thought) Nervous: brain, spinal cord, nerves Digestive: mouth, esophagus, stomach, intestines, etc Respiratory: nose, trachea, lungs, Circulatory: hear, blood, blood vessels, Skin: skin, hair, nails, sweat glands, oil glands Excretory: kidney, bladder, (going to the bathroom) Immune: lymph nodes, thymus, spleen Endocrine: pititutary gland, thyroid gland (secrete hormones) Reproductive: testes, ovaries, urethra, prostate
Optimising body shape
Some animals have body shapes that allow them to put many of their cell in contact with the environment which means that they can rely on diffusion e.g. the gastrovascular cavity in hydras, jellyfish and other cnidrians or the flat body in planarians
Arthropod anatomy
Sucess has been attributed to body plan which includes a segmented body (developmental flexibility), jointed appendages and a hard exoskeleton
Mesozoic era
The era about 251-65.5 MYA which started with a mass extinction event (84% genera disappear). The surviving animals spreas into new habitats (coral reefs appear). Descent with modifcation in vertebrates which resulted in the origin of wings in birds, the emergence of small and large dinosaurs
Cenozoic era
The era from 65.5 MYA to present which starts with a mass extinction which killed 47% of life. This resulted in the disappearance of large, nonflying dinosaurs and marine reptiles which lead to the rise of large mammals that exploited the vacated ecological niches.
Endoderm
The inner germ layer that develops into the lining of the digestive and respiratory systems
Deuterostome vs. Protostome
The main difference between protostomes and deuterostomes is at the point of the blastopore. In protostomes, the blastopore develops into the mouth and the opposite cavity develops into the anus. In deuterostomes (the group that includes vertebrates and echinoderms), the blastopore develops into anus.
dorsal hollow nerve cord
The nerve cord found in all chordates that forms the spinal cord and brain (CNS) in adults
blastopore
The opening of the archenteron in the gastrula that develops into the mouth in protostomes and the anus in deuterostomes
Ectoderm
The outer germ layer that develops into skin and nervous tissue
Paleozoic Era
The part of geologic time 570-245 million YA Animal where diversity continued to increase but this was also punctuated by mass extinction events. Vertebrates (fish) emerged as top predators in the marine food web. The land started to be colonised by fungi and plants (500 MYA), arthropods (450 MYA), vertebrates (amphibians and amninotes) (365 MYA)
Porifera
The phylum of pore-bearing sponges. They are sessile (i.e. don't move), often brightly-covered and are filter feeders - they trap food particles in the water as they draw it through their body. Their size ranges from mm to m.
Homeostasis
The steady-state physiological condition of the body e.g. temperature and solute concentration
Thermoregulation by function
Thermogenesis in endotherms e.g. muscle activity and increased metabolic activity. Evaporative cooling (sweat) too.
What distinguishes an animals
They are multicellular, eukaryotic, heterotrophs, dont have a cell wall and have nervous and muscular tissue. They mostly reproduce sexually with a dominant diploid stage and many animal's life cycles include a larval stage that metamorphoses into an adult through the expression of hox genes.
Cnidaria anatomy
They have a aac with central digestive compartment (gastrovascular cavity) and only a single opening that functions as both a mouth and anus. There are two variation: the mostly sessile polyp and mobile medusa
Class Amphibia
Three major order: 1) Salamanders (order Urodela: "tailed ones") 2) Frogs (order Anura: "tailless one") 3) Caecilions (order Apoda: "legless ones)
Coordinating functions
Tissues, organs and organ systems must work together in coordination. Two internal communication systems are endocrine and nervous.
Cyclostomes
Two clades of aquatic vertebrate chordates that consist of living jawless vertebrates i.e. hagfishes and lampreys
convergent evolution
Unrelated organisms evolve similar traits as a result of adaptation to similar environments i.e. Water is 1000 x denser than air and far more viscous which means any bump on an animal's body will create drag
Pharyngeal slits or clefts
Used for suspension feeding in invertebrates. Develops into gills in non-tetrapod vertebrates or develops into parts of ears and necks of tetrapods (four-limbed vertebrates)
Mollusca
Very diverse phylum (100 000 species) of soft-bodied organisms that secret hard protective shell made of calcium cabornate (note: slugs, squids and octopi have (reduced) internal shells or have lost it altogether). Most molluscs have separate sexes except snail many of which are hermaphrodites. Life cycle of many marine molluscs include a trochophore larval stage
Ecdysozoa
Very diverse supergroup of protostomes which includes 8 phyla and contain more known species than all other animals, protists, fungi and plant groups combined. Includes animals that shed tough external coast the grow via ecdysis (moulting). Two of the largest phyla are nematodes (roundworms) and arthropods
Echinoderm water vascular system
Water enters through pore, flows into ring canal in centre, then down five radial canals running down entire arm into infltable tubes
Mesoderm
middle germ layer; develops into muscles and other organs and body cavity
archentron
primitive gut
Hox genes
series of genes that controls the differentiation of cells and tissues in an embryo
Tetrapods
vertebrate animals that have four feet, legs or leglike appendages. Includesamphibians, reptiles and mammals. First appeared 365 MYA after colonisation of land and clearly evolvef from find shown in fossil records
