Studied by 12 PeopleTags & Description
-Multicellular eukaryotes -Heterotrophs -Cells lack cell walls -Collagen
What is an animal?
-comprises fibers in connective tissues -most abundant protein in animal bodies -flexible, high tensile (stretchy), strength, high elastic resilience (returns energy)
What is collagen?
-skin: dense irregular arrangement of collagen -ligament (connect bones): collagen arranged in sheets -tendon (connects muscles to bones): cable-like arrangement of collagen
What are the different collagen arrangements?
-sexually with diploid stage dominating the life cycle -sperm fertilizes egg → zygote zygote undergoes rapid cell division → cleavage
How do animals reproduce?
-collections of specialized cells with a common function, isolated from other tissues by membranous layers
What are tissues?
-germ layers give rise to the tissues and organs of the animal embryo
What are germ layers?
-cell cleavage
What leads to a blastula?
-hollow blastula undergoes gastrulation -forms a gastrula with layers of embryonic tissues
What undergoes gastrulation and what does it form?
-ectoderm: covers embryo's surface -endoderm: innermost germ layer and lines the developing digestive tube →archenteron -archenteron
What are the different embryonic tissue layers in a gastrula?
-sponges
What animals lack true tissues?
-have ectoderm and endoderm -coral, jellyfish, comb jellies
What are diploblastic animals and give some examples.
-have ectoderm, endoderm, and mesoderm layer (in between ectoderm and endoderm)
What are triploblastic animals?
-multicellular animals other than sponges and cnidarians -Characteristics: bilateral symmetry, cephalization (organization of senses and locomotion toward a head region)
What are bilaterians and what are some of their characteristics?
-larva: sexually immature and anatomically distinct from an adult; undergoes metamorphosis -juvenile: resembles an adult but is not sexually mature
What are some characteristics of a larval stage?
-(535 to 525 million years ago) marks the earliest fossil appearance of many major groups of living animals -new predator-prey relationships -rise in atmospheric oxygen -evolution of the Hox gene complex
What is the Cambrian explosion and what are some possible causes?
-regulate other genes and control the development of body form
What are Hox genes?
-deuterostomes -lophotrochozoa -ecdysozoa
What are the three major groups that separate bilateral animals?
-cell proliferation following fertilization by spiral cleavage -coelom (body cavity) forms within the middle tissue germ layer -initial opening into the gut becomes the mouth
What is a protostome?
-cell proliferation following fertilization by radial cleavage -coelom forms from outpocketing of the middle tissue germ layer -initial opening into the gut becomes the anus
What is a deuterostome?
-smallest genome -only four cell types -no symmetry -no organs -no muscles -no nervous system
What are the characteristics of the phylum placozoa?
-sponges -Characteristics: specialized cell types but no true tissues; sessile → no locomotion; collar cells → responsible for movement, in flagella, create water currents that move through the body of the sponge
What are some characteristics of the phylum porifera and give an example of an animal in this phylum.
-tiny calcium or silica structures -support sponge body
What are spicules and what animal has them?
-function in digestion of food particles pulled from the water current by the collar cells
What are amoebocytes?
-modern choanoflagellates → protists
What does the hypothesized ancestor responsible for animal diversity resemble?
-sponges -sperm is released into the environment
What are hermaphrodites and what animal is one?
-jellyfish, anemones, corals -radial symmetry -two specialized cell layers (tissues) -nerve cells -feeding is done by capturing food particles or prey from water
What are some characteristics of the phylum cnidaria and what are some animals in this phylum?
-sessile polyp -free-swimming medusa
What are the two body forms for cnidarians?
-way to get prey by launching a venomous spine
What is a nematocyst?
-lophophore: horse-shoe shaped feeding structure or -trocophore: ciliated larva
What are characteristics of the lophotrochozoa?
-flatworms -lack circulatory, respiratory, and skeletal systems -coelom is absent and gut is incomplete -large range in size (less than 1 mm to several m)
What are characteristics of the phylum platyhelminthes and what are some examples of this phylum?
-turbellaria -monogenea -trematoda -cestoda
What are some of the classes of the phylum platyhelminthes?
-mostly marine, some fresh water, a few terrestrial -predators and scavengers -body surface is ciliated -mostly hermaphordites but can also reproduce asexulally -flatworms, planarian
What are some characteristics of the class tubellaria and what are some animals in this class?
-marine and freshwater parasites -most infect external surfaces of fishes (skin and gills) -life history is simple -ciliated larva starts infection on host -unciliated synctial outer layer (cells connected so that cytoplasm is shared -monogeans
What are some characteristics of the class monogea and what are some animals in this class?
-parasites, mostly vertebrates -two suckers attach to host (mollusc and vertebrate) -most life cycles include intermediate and finals hosts -infections from this class can cause pain, anemia, dysentery, and liver damage -trematodes (flukes)
What are some characteristics of the class trematoda and what are some animals in this class?
-parasites of vertebrates -scolex (hooked structure) attaches to host (via intestine) -proglottids produce eggs and break off after fertilization -no head, digestive system, and no sense organs -life cycle with one or more intermediate hosts -proglottids → comprise the body and contains both male and female sex organs -tapeworms
What are some characteristics of the class cestoda and what are some animals in this class?
-Rotifer -max size is 3mm (super small) -wide range of aquatic and marine habitats -some can survive in extremely dry and cold conditions -predators, parasites, filter feeders (some are sessile) -mouth has hard, muscular jaws -have separate sexes or are asexual
What are some characteristics of the phylum syndermata and an example of an animal in this phylum?
-need moisture in habitat, but has a huge range of habitats -large variety of sizes -one of the largest animal phyla -used as food, crop pests, and intermediate hosts for human parasites -protective mantle enclosing a mantle cavity and muscular foot -radula → scraping, tongue-like feeding organ; in all major mollusc classes except bivalves
What are some characteristics of the phylum mollusca?
-calcium carbonate
What are mollusc shells composed of?
-polyplacophora -gastropoda -bivalvia -cephalopoda
What are some of the classes of the phylum mollusca?
-marine -shell with 8 plates -foot used for locomotion -radula -no head -chitons
What are some characteristics of the class polyplacophora and what are some animals in this class?
-marine, freshwater, or terrestrial -head present -symmetrical body, usually with a coiled shell -shell reduced or absent -foot for locomotion -radula -mostly herbivores but some are scavengers or active predators -some have a complex genital apparatus from the side of its head which hermaphroditic slugs use to pass sperm -some snails have "love darts" to inject hormones into their mate to increase the success of their sperm in fertilizing eggs -snails, slugs
What are some characteristics of the class gastropoda and what are some animals in this class?
-marine and freshwater -flattened shell with two valves -head reduced -paired gills → modified for filter-feeding -no radula -locomotion is by extension and anchoring of the foot or by propelling water between the valves (shells) -clams, mussels, scallops, oysters
What are some characteristics of the class bivalvia and what are some animals in this class?
-marine predators -head surrounded by grasping tentacles, usually with suckers -shell external, internal, or absent -mouth with or without radula -locomotion via jet propulsion; foot is modified into a siphon for propulsion -sexes are separate -highly developed nervous and sensory systems -squids, octopuses, cuttlefishes, chambered natiluses
What are some characteristics of the class cephalopoda and what are some animals in this class?
-true coelom -closed circulatory system -body plan exhibits distinct repetition of segments → metameric -reproduction by separate sexes, hermaphroditic sexual reproduction, or by fission and regeneration -marine
What are some characteristics of the phylum annelida?
-errantia -sedentaria
What are the two major clades of the phylum annelida?
-mostly mobile and marine -pair of paddle/ridge-like parapodia (beside feet) on each body segment each parapodium (foot) has numerous chaetae → bristles made of chitin
What are some characteristics of the clade errantia?
-less mobile than errantians -some burrow into substrate or live in protective tubes -tube-dwelling sedentarians have elaborate gills or tentacles used for filter feeding -leeches and earthworms
What are some characteristics of the clade sedentaria?
-parasites/predators -lack chaetae and have suckers on anterior and posterior ends -blood-sucking leeches produce an anti-clotting enzyme, hirudin, to facilitate feeding
What are leeches?
-ecdysis → periodic shedding of a cuticle
What is a defining characteristic of the ecdysozoa?
-cuticle → non-living external layer secreted by the epidermis -cuticle is periodically shed as the nematode grows → ecdysis -only have longitudinal muscles -hydrostatic skeleton → resists compression and transmits muscular forces due to the high internal pressure in the pseudocoelom allowing it to function with the cuticle
What are some characteristics of the phylum nematoda?
-ascaris lumbricoides -necator americanus (hookworm) -trichinella spiralis -caenorhabditis elegans
What are some animals that are part of the phylum nematoda?
-largest and most common parasite of the human intestine -one female can lay over 200,000 eggs each day -intestinal infection is acquired by ingesting eggs present in the soil
What are some characteristics of ascaris lumbricoides?
-juveniles feed on bacteria in the soil and infect humans by penetrating the skin -adults feed on blood sucked from the lining of the intestines
What are some characteristics of necator americanus (hookworm)?
-responsible for the potentially lethal disease trichinosis contracted by consuming undercooked pork -juveniles enter muscle cells and alter the host's gene expression to change the muscle into a nurse cell that protects and nourishes the nematode
What are some characteristics of trichinella spiralis?
-most studied "model organisms"
What are some characteristics of caenorhabditis elegans?
-tropical predators that prey on ground-dwelling insects, snails, and worms -unjointed appendages and a body form that changed very little -paired slime glands spray an entangling fluid to catch prey -onychophorans or velvet worms
What are some characteristics of the phylum onychophora?
-water bears; microscopic inhabitants of water films on mosses or marine sands that feed by sucking fluids from other tiny animals or plants -cryptobiosis → state of suspended metabolism -in cryptobiotic state, tardigrades can survive: heating to 149°C and cooling to -272°C; radiation; lack of oxygen
What are some characteristics of the phylum tardigrada?
-cuticle hardened by proteins -exoskeleton made of chitin -jointed appendages that are modified for special functions -segmented bodies into functional units → tagmata -open circulatory system emptying into body cavity → hemocoel -complete digestive system, complex muscle and nervous systems -respiration through a complex system of air canals → trachea
What are some characteristics of the phylum arthropoda?
-cheliceriformes -myriapoda -hexapoda -crustacea
What are some of the subphyla of the phylum arthropoda?
-body having one or two main parts -six pairs of appendages -mostly terrestrial or marine -horseshoe crabs, spiders, scorpions, ticks, mites
What are some characteristics of the subphylum cheliceriformes and what are some animals in this subphylum?
-distinct head bearing antennae and chewing mouthparts -terrestrial -millipedes and centipedes
What are some characteristics of the subphylum myriapoda and what are some animals in this subphylum?
-body divided into head, thorax, and abdomen -antennae present -three pairs of legs and usually two pairs of wings -mostly terrestrial -insects, springtails
What are some characteristics of the subphylum hexapoda and what are some animals in this subphylum?
-body of two or three parts -antennae present -chewing mouthparts -three or more pairs of legs -elaborate serial homology -mostly marine and freshwater -crabs, lobsters, crayfishes, shrimps
What are some characteristics of the subphylum crustacea and what are some animals in this subphylum?
-study of insects is called entomology -openings in the exoskeleton lead to a system of trachea and tracheoles that supply the body with oxygen -growth in insects result in molting of exoskeleton; the life stages between molts are called instars -has the protein resilin which plays a large role in locomotion -flexible chitinous exoskeleton -asynchronous flight muscles
What are some characteristics of insects?
-ametabolous: growth without major change in form -hemimetabolous: nymph stage is followed by increased development of wings from buds with each successive molt -holometabolous: complete metamorphosis from stages specialized for feeding to stages specialized for mating and dispersal
What are the three stages of insect development?
-hemichordata -echinodermata -chordata
What phylums are classified as deuterstomes?
-asteroidea -ophiuroidea -echinoidea -crinoidea -holothuroidea
What are some classes in the phylum echinodermata?
-marine animals -secondarily evolved radial symmetry from a bilateral ancestor (larva are still bilateral) -calcium-containing endoskeleton (internal skeleton) of plates or tiny bony elements -none of the echinoderms are parasites -water-vascular system for movement -fluid is pushed from muscular ampullae into tube feet causing them to extend -external surface is covered with spines and pedicellariae → tiny jaws that keep the surface clear of debris and parasites -catch collagen → unique connective tissue of echinoderms, changes rapidly between solid and liquid states in response to stimulation from the nervous system
What are some characteristics of the phylum echinodermata?
-star-shaped body with multiple arms -mouth directed to substrate -sea stars
What are some characteristics of the class asteroidea and what are some animals in this class?
-distinct central disk -long, flexible arms -incomplete digestive system -brittle stars
What are some characteristics of the class ophiuroidea and what are some animals in this class?
-roughly spherical or disk-shaped -no arms -five rows of tube feet -mouth ringed by complex, jaw-like structure -sea urchins, sand dollars
What are some characteristics of the class echinoidea and what are some animals in this class?
-feathered arms surrounding upward-pointing mouth -sea lilies, feather stars
What are some characteristics of the class crinoidea and what are some animals in this class?
-cucumber-shaped body -five rows of tube feet -reduced skeleton -no spines -secondarily evolved bilateral symmetry -can digest organic matter in sediment and can expel and regenerate their digestive system -sea cucumbers
What are some characteristics of the class holothuroidea and what are some animals in this class?
-notochord → semi-rigid rod of cells enclosed by a fibrous sheath that functions as a skeletal element -dorsal, hollow nerve cord → runs along the length of the body -pharyngeal slits or clefts → openings in the pharyngeal cavity (throat) to the outside of the animal; leads to the structures of the middle ear, tonsils, and internal gills -muscular, post-anal tail → aquatic locomotion
What are the characteristics of the phylum chordata?
-cephalochordata -urochordata
What are the two chordate lineages that diverged early in the evolution of vertebrates?
-lancelets -small, thin filter-feeders -found on the sandy bottoms in coastal waters -lack gills and heart -closed circulatory system
What are some characteristics of the cephalochordates?
-also known as tunicates -more closely related to other chordates than lancelets -as an adult, draws in water through an incurrent siphon which filters food particles
What are some characteristics of the urochordata?
-backbone -two or more sets of hox genes that regulate anterior-posterior development -embryos have neural crest cells that give rise to a variety of structures (bones, cartilage)
What are some characteristics of vertebrates?
-Scavengers: myxini, hagfish, petromyzontida -Parasites: lampreys
What are some examples of jawless fish (cyclostomes)? Which ones are scavengers and which ones are parasites?
-notochord is the only "backbone" -cartilage braincase rather than bone -no paired fins -no stomach -partially open circulatory system (4 hearts)
What some characteristics of the myxini?
-fibrous and cartilage skeleton -cartilage braincase -no paired fins -distinct stomach -closed circulatory system with single heart
What are some characteristics of the petromoyzontida?
-glands that secrete huge amounts of mucous and protein threads that surround the body in defensive slime
What are some characteristics of hagfishes?
-attach to fish by suction and rasp a wound through the skin with their spiny tongues -anticoagulant allows lamprey to acquire blood and body fluids while attached to the host
What are some characteristics of lampreys?
-chordates with jaws -sharks, ray-finned fish, lobe-finned fish, amphibians, reptiles (including birds), mammals -placoderms → earliest gnathostomes in fossil records
What are gnathostomes and what are some examples?
