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Bio 211 Exam 2
animals
| Question | Answer |
|---|---|
| What are some of the characteristics of animals? | Multicellular + heterotrophic eukaryotes; obtain nutrition through ingestion; no cell walls, held together by glycogen + a structural protein; most possess specialized tissues (nervous and muscle) |
| What are some features of the animal life cycle? | Most reproduce sexually; diploid stage is dominant; after sperm fertilizes egg a diploid zygote is formed; early embryo undergoes cleavage and includes multiple stages (blastula, gastrula) |
| What is cleavage? | Mitotic cell division without cell growth (no change in original size) |
| What is gastrulation? | A rearrangement of the embryo; folds into the blastocoel, forming layers (like germ layers) |
| What are the germ layers that are formed after gastrulation? | Ectoderm, endoderm, mesoderm |
| What is ectoderm? | Outer layer of tissue that gives rise to the outer covering and the central nervous system |
| What is endoderm? | Inner layer of tissue that lines the digestive tube (archenteron) and the organs derived from it |
| What is mesoderm? | Middle layer of tissue that develops into muscles and most organs |
| What are Homeoboxes (Hox)? | The DNA sequences that regulatory genes contain; all eukaryotes have genes that regulate the expression of other genes |
| What is the Neoproterozoic Era? | During 1 billion - 542 mya; the oldest accepted animal fossils are around 565 to 550 mya; known as the Ediacaran biota; consisted of multicellularity, eukaryotes, radial forms, and many segments |
| What is the Cenozoic Era? | During 65.5 mya - present; mass extinctions occurred, large dinosaurs disappeared; mammals exploited open niches; the global climate gradually cooled |
| What is the Paleozoic Era? | During 542 - 251 mya; during the Cambrian period; species from a few phyla ranging to half of all extant phyla |
| What is the Cambrian Explosion? | Explains the new predator-prey relationships through natural selection, rise in atmospheric O2, and the evolution of the Hox gene complex |
| What are animal groups defined by? | Symmetry, organization of tissues, type of body cavity, and the pattern of embryonic development |
| What is body symmetry? | Consists of asymmetry, radial symmetry, and bilateral symmetry |
| What is radial symmetry? | Any slice through the central axis is a mirror image which has a top and bottom, and no right or left sides |
| What is bilateral symmetry? | Only one slide through the central axis is a mirror image which has a top and bottom and right and left sides; most animals acquire this, typically those that have a dorsal and ventral side and an anterior and posterior end |
| What are tissues? | Collections of specialized cells isolated from others by membranous layers; sponges lack these; all other animals develop these types of layers called germ layers |
| What does diploblastic mean? | A group that has only two germ layers, an ectoderm and endoderm |
| What does triploblastic mean? | A group that has all three germ layers (like humans) |
| At what developmental stage should one be able to first distinguish a diploblastic from triploblastic embryo? | Gastrulation |
| What are the two types of embryo tissue? | Diploblastic and triploblastic |
| What are the types of body cavities? | Coelomates, pseudocoelomates, and acoelomates; these are only found in triploblastic animals |
| What is a coelom? | A fluid-filled space that separates the digestive tract from the outer body wall that is completely lined with mesoderm |
| What is a coelomate? | A true/real coelom; the body cavity is completely lined by mesoderm tissue |
| What is a pseudocoelomate? | A "false" coelom; the body cavity is not completely lined by mesoderm tissue |
| What is an acoelomate? | No coelom; no body cavity |
| Why is having a body cavity important? | Fluids help to cushion organs to prevent injury; it acts like a skeleton in some soft-bodied animals; provides space for organs to grow and move independently from the outside of the body |
| What are the two major animal groups that are defined by the blastopore? | Protostomes and deuterostomes |
| What is the pattern of embryonic development in protostomes? | The development cleavage is spiral and determinate; the blastopore becomes the mouth of the digestive system |
| What is the pattern of embryonic development in deuterostomes? | Development cleavage is radial and indeterminate; the blastopore becomes the anus of the digestive system |
| What are the three major bilaterian clades? | Deuterostomia, Lophotrochozoa, and Ecdysozoa |
| What is Clade Deuterostomia? | Includes the vertebrates; consists of fish, amphibians, reptiles, birds, and mammals; overall makes up less than 5% of the known animal species on Earth |
| What is Clade Ecdysozoa? | Includes protostome animals that secrete external skeletons (exoskeletons); as the animal in this group grows, it sheds its exoskeleton and secretes another |
| What is Clade Lophotrochozoa? | Includes protostome animals that have a "trochophore" larva before metamorphosis or a "lophophore" stage as an adult |
| What does lophophore mean? | Refers to a ciliated tentacle structure in brachiopoda |
| What does trochophore mean? | Refers to the ciliated band in molluscs and annelids |
| What are some characteristics of sponges? | Sedentary; live in both fresh and marine waters; lack true tissues; suspension feeders |
| What are Phylums Calcarea and Silicea (Phylum Porifera)? | Has 5,500 species mostly marine; asymmetrical; no tissues or organs (no nerves, muscles, or germ layers); body wall has two cell layers separated by a jelly-like mesohyal layer; choanocytes as inner cell layer, epidermis as outer cell layer |
| What are suspension feeders? | Organisms that filter food from the water; body is like a sac perforated with holes (pores); water flows in through the pores into the spongocoel and then out the osculum |
| How do sponges create a water current for filter-feeding? | By choanocytes, a unique cell type found only in Porifera that has long flagellum and is structurally similar to the choanoflagellates (protists) that are considered to be the ancestor to all animals |
| How does asexual and sexual reproduction occur in sponges? | Most are hermaphrodites, meaning that they produce eggs and sperm and most exhibit sequential hermaphroditism; sperm are released into the water then collected by another sponge; larvae have cilia for dispersal, and can reproduce asexually by budding |
| What are Cnidarians (Phylum Cnidaria)? | Include jellyfish, corals, hydras, and sessile and motile forms; basic body plan is a sac with a central digestive compartment (gastrovascular cavity); a single opening functions as both mouth and anus; one of the oldest lineages in clade Eumetazoa |
| What are some characteristics of Cnidarians? | 10,000 species mostly marine; have true tissues like muscles and nerves; are Eumetazoans; diploblastic; radial symmetry; two body forms, sessile (mouth up) and motile medusa (mouth down) (both body forms are diploid) |
| Why are Cnidarians predators? | They have cnidocytes, and some have nematocytes; they are carnivores that have tentacles armed with cnidocytes |
| What is a cnidocyte? | A specialized cell type found only in Cnidaria that can explode outward |
| What is a nematocyte? | Some cnidocytes have these, which are able to inject poison |
| What are some characteristics of corals? | Found only as polyps in shallow tropical oceans; are symbiotic dinoflagellates; secrete hard external skeletons of calcium carbonate; create ecosystems that are used by many other species |
| What are Ctenophores? | Have eight rows of fused cilia called "combs" arranged along the sides of the animal |
| What are some characteristics of Bilateria? | Bilateral symmetry on left and right side; triploblastic; are coelomates (some); have three major clades: Lophotrochozoa, Ecdysozoa, and Deuterostomia |
| What are Lophotrochozoans? | They have the widest range of body forms; include flatworms, rotifers, ectoprocts, brachiopods, molluscs, and annelids |
| What does the Lophotrochozoan body plan consist of? | Bilateral symmetry; triploblastic; protostomes; a life stage with a ciliated feeding structure either as larva ("trochophore") or as an adult ("lophophore") |
| What is Phylum Platyhelminthes and what are some characteristics? | The flatworms; bilateral symmetry, cephalization; flattened dorsoventrally; acoelomate; incomplete digestive system (gastrovascular cavities) or no digestive system; no organs for circulation (diffusion); central nervous system with sensory organs |
| What are the classes of Phylum Platyhelminthes? | Free-living: Class Turbellaria (planarians); Parasitic: Class Monogenea (monogeneans), Class Trematoda (flukes), Class Cestoda (tapeworms) |
| What is Class Tubellaria? | Consists of free-living flatworms with most being marine |
| What are parasitic flatworms? | Monogeneans and trematodes live as parasites in or on other animals; most monogeneans are parasites of fish; trematodes parasitize a wide range of hosts |
| How to distinguish between free-living vs. parasitic animals? | Parasites use host organisms + feed off of host; host is necessary to complete life cycle; intermediate host is where larvae develop; final host is where sexual reproduction occurs; there is an increased reproductive effort in parasites |
| What does reproductive effort mean? | Describes the amount of body that is dedicated to reproduction |
| What are some characteristics of parasites? | High reproductive rate; very mobile larval stages; attachment organs (hooks, suckers); reduction of organs or organ systems (ex: no digestive tract); external covering that is tough or camouflages from host's immune system |
| What is Class Trematoda? | The flukes; describes parasites that attach to hosts using suckers; many species have complex life cycles involving multiple hosts (intermediate and final hosts) |
| What is Class Cestoda? | The tapeworms; describes parasitic flatworms found in the intestines of vertebrates, including humans; no digestive system, uses absorbed materials that are pre-digested by the host; can be over 20 meters in length |
| What are the two components that adult cestodes have? | The scolex --> head with attachment organs like hooks and suckers; and the proglottids --> the body segments with sex organs |
| What are Brachiopods (Phylum Brachiopoda)? | Have a horseshoe-shaped crown of ciliated tentacles, known as a lophophore, that surround the mouth; resemble clams, but have shell halves that are dorsal and ventral rather than lateral |
| What are Ectoprocts (Bryozoans)? | Colonial animals that resemble plants |
| What are the Molluscs (Phylum Mollusca)? | Include snails, slugs, oysters, clams, octopuses, and squids; most are marine; soft-bodied; most secrete a hard protective shell made of calcium carbonate; 93,000 named species; second largest animal phylum |
| What does the Molluscan body plan consist of? | A foot; a mantle that covers visceral mass and may secrete shell; and visceral mass (internal organs) |
| What is Class Gastropoda? | Consists of snails, slugs, and sea slugs; the most diverse Molluscan class; about 40,000 named species; takes up 3/4 of all living species of Molluscs |
| What is Class Bivalvia? | Consists of clams, cockles, mussels, oysters, and scallops; both marine and freshwater species, no terrestrial species; two shells; most are filter-feeders; have a muscular foot for movement and digging into sediments |
| What is Class Cephalopoda? | Consists of squids, octopus, cuttlefish, and nautilus |
| What is Phylum Annelida? | Includes segmented worms; about 16,500 named species; found in marine, freshwater, and damp soils; range in size from less than 1 mm to over 3 meters long |
| What are the three classes of Annelida? | Oligochaeta, Polychaeta, and Hirudinea |
| What are Oligochaetes? | They are named for their relatively sparse chaetae, or bristles, made of chitin; include earthworms and a variety of aquatic species |
| What is the ecological importance of earthworms? | They eat their way through soil; digest organic matter by producing casts; tunnels left behind by earthworms help aerate soil by creating pores for gas and water to penetrate the soil, and passageways for other soil organisms |
| What are Polychaetes? | They possess paddle-like parapodia that function in locomotion and defense |
| What are Hirudinea (leeches)? | They live in freshwater, marine, and terrestrial habitats; lack bristles; have two suckers, one on each end; some are parasites that feed on blood |
| What are some characteristics of Clade Ecdysozoa? | Bilateral symmetry; triploblastic; protostomes; molt their exoskeletons during growth |
| What are Nematodes (Phylum Nematoda)? | Includes roundworms; are among the most widespread of all animals; found in most aquatic habitats, in soil, in moist plant tissues, and in the body fluids and tissues of animals |
| What are some characteristics of Nematodes? | They are covered by an exoskeleton (cuticle) made of collagen; move by contracting longitudinal muscles against the cuticle ("thrashing"); don't have segmented bodies; are pseudocoelomates; have a complete digestive system (mouth and anus) |
| What is Phylum Arthropoda? | "Jointed feet"; the largest animal phylum; over 1 million species named; mostly insects; have an exoskeleton made of chitin; grow by shedding their exoskeleton by molting; open circulatory system; have organs specialized for gas exchange |
| What four characteristics are Arthropod success and diversity related to? | A segmented body, a hard exoskeleton, jointed appendages, and a well-developed head (cephalization) and sensory organs |
| What is a segmented body in Arthropods? | Describes an evolutionary trend to reduce the number of segments by fusion as a more efficient body plan; division of labor (reproduction, feeding, movement) |
| What is a hard exoskeleton in Arthropods? | Is made of chitin; provides protection; prevents water loss; provides attachment sites for muscles |
| What are jointed appendages in Arthropods? | Are very movable with multiple joints per leg; an evolutionary trend for them to become more specialized for specific functions like feeding, movement, and reproduction |
| What is a well-developed head and sensory system in Arthropods? | Describes eyes, olfactory (smell), and antennae (smell and touch) |
| What are the four major subphyla that Arthropods have? | Chelicerata, Myriapoda, Crustacea, and Insecta (Hexapoda) |
| What is Clade Chelicerata? | A claw-like feeding appendage which puncture, not chew; most are terrestrial and belong to the Class Arachnida (spiders, ticks, scorpions); have two main body regions --> the abdomen and cephalothorax (head + thorax); four pairs of legs; no antennae |
| What is Class Crustacea? | About 40,000 named species; mostly aquatic, marine and freshwater; includes crabs, shrimp, barnacles, isopods, and copepods; have two body regions, cephalothorax and abdomen; two pairs of antennae; chewing mouthparts; branched appendages; >5 pairs of legs |
| What is Class Myriapoda? | Includes millipedes and centipedes; all living species are terrestrial; have two body regions: head + abdomen, and a highly segmented abdomen; one pair of antennae; have many legs |
| What is Class Insecta (Hexapoda)? | The most successful group of Arthropods; more species than all other groups of organisms combined; found in almost every terrestrial and freshwater habitat |
| What are some characteristics of Class Insecta (Hexapoda)? | Have three main body regions: head + thorax + abdomen; three pairs of legs (six legs); one pair of antennae; many species have one or two pairs of wings |
| What are the three major adaptations that may have been key to the success of insects? | Flight, specialized mouth parts (chewing, sucking, lapping, piercing, etc.), and metamorphosis (reduces competition between parent and offspring) |
| Why do insects have a huge ecological and economic effect? | Many species pollinate plants, including crop plants; they are vectors for disease, such as malaria, elephantisis, and chagas; they compete with humans for food --> in the U.S., farmers spend billions each year on pesticides |
| What is the plague of locust? | Describes a locust that would eat its own body weight each day |
| What are vertebrates? | About 52,000 species; include the heaviest and largest animals to ever exist on Earth; members of the Phylum Chordata |
| What are the four characteristics that all chordates have at some developmental stage? | A notochord; a dorsal, hollow nerve cord; pharyngeal slits; and a muscular post-anal tail |
| What is a notochord in chordates? | A flexible rod located between the nerve cord and the gut that provides skeletal support for muscle attachment |
| What is a dorsal hollow nerve cord in chordates? | Is unique to chordates, since other animals have a solid one that is usually ventrally located; it develops into the central nervous system (brain and spinal cord) |
| What are pharyngeal slits in chordates? | Openings to the outside of the body at the pharynx (region just behind the mouth); allows water that enters the mouth to exit without passing through the gut in invertebrate species; modified for gas exchange or other functions in vertebrates |
| What is the muscular post-anal tail in chordates? | Consists of skeletal elements (notochord) and muscles; lost during embryonic development in many species |
| What is the Subphylum Urochordata? | Consists of Tunicates ("sea squirts"); are filter feeders with incurrent and excurrent siphons |
| What are some characteristics of Tunicates? | They have no notochord, nerve cord, or tail, however, these features are present in their larval form (may only last a few minutes); undergo radical metamorphosis in which most traits disappear in the adult stage |
| What are craniates? | Describes chordates with a head, which opened up a new type of feeding behavior called active predation; have a more extensive skull, vertebrae enclosing a spinal cord, and fin rays in aquatic species |
| What are neural crest cells? | These are one unique feature of craniates; these disperse and give rise to a variety of structures |
| What are Hagfishes (Class Myxini)? | The least derived craniate lineage that still survives; lack jaws and vertebrae |
| What is the Subphylum Vertebrata? | Includes some large and rather obvious animals that are quite familiar to us; these represent less than 5% of the known animal species on Earth |
| What are some major events in Vertebrate history? | Development of jaws, bone, and lungs; more complex circulatory systems; four-legged (tetrapod) terrestrial vertebrates; reproductive adaptations to life on land; there are some groups that do not have these traits |
| What are Lampreys? | This is the oldest vertebrate group, and are jawless; they have a skeleton made of cartilage that does not contain collagen |
| When were jaws developed in Vertebrates? | By the origin of the Chondrichthys |
| What are Gnathostomes? | Describes all vertebrates that have jaws which enable animals to firmly grip and slice food items; appeared in fossil record about 470 mya; also have paired fins and a tail for locomotion |
| What does Gnathostomata include? | Chondrichthys (cartilaginous fishes like sharks and rays), several groups of bony fishes, amphibia, reptilia (plus birds), and mammalia |
| What are some characteristics of Gnathostomes? | An enlarged forebrain; enhanced senses of smell and vision; the lateral line system in aquatic species |
| What is Clade Osteichthyes? | Where the vast majority of vertebrates belong; species have an ossified (bony) endoskeleton; aquatic species (fishes); control buoyancy with an air sac known as a swim bladder; skin is covered by flattened, bony scales |
| What is Class Actinopterygii? | Consists of ray-finned fishes; 27,000 species; fins are modified for maneuvering, defense, and other functions |
| What are lobe-fins (Class Actinistia and Dipnoi)? | Consist of muscular pelvic and pectoral fins; surviving lineages include the coelacanths, lungfishes, and tetrapods |
| What are tetrapods? | Large group of gnathostomes that have developed limbs and feet; limbs can support weight; pelvis fused to vertebrae; no gills slits |
| What are some specific adaptations of tetrapods? | The head is separated from the body by a neck; head can swing from side to side; bones of the pelvic girdle (hind legs) are fused to the backbone; development of ears |
| What is Class Amphibia? | "Two-lives"; about 6,150 species; include frogs, salamanders, and caecilians; first vertebrates to be on land (350 mya); have gas permeable skin (water loss); part of the life cycle needs water like eggs and larvae; metamorphosis (herbivore to carnivore) |
| What are salamanders? | They acquire tails (Order Urodela) |
| What are frogs and toads? | They lack tails (Order Anura) |
| What are Caecilians? | They are legless and resemble worms (Order Apoda) |
| What are some characteristics of Amphibians? | They generally rely heavily on their moist skin for gas exchange; fertilization is external in most species; eggs lack a protective shell; typically lay eggs in water or moist terrestrial environments |
| What are "Amniotes"? | Refers to a type of egg (post-fertilization); have specialized extraembryonic membranes; allows for embryonic development to occur on land; reduced dependence of tetrapods for reproduction in an aqueous environment; includes reptiles, birds, and mammals |
| What is an amniotic egg? | Describes membranes that are used for gas exchange, waste storage, and nutrient transfer; the fluid protects the embryo; some species acquire a shell |
| What are some characteristics of "Amniotes"? | They have less permeable skin; can use their rib cage to ventilate the lungs; could abandon breathing through their skin and develop less permeable skin, therefore conserving water |
| What is Clade Reptilia? | Includes tuataras, turtles, lizards, snakes, crocodilians, and birds; numerous extinct groups (dinosaurs); scaly skin containing keratin to reduce water loss; most lay shelled eggs on land; most are ectothermic, but birds are endothermic |
| What does ectothermic mean? | The process of absorbing external heat as the main source of body heat |
| What does endothermic mean? | The process of generating body heat through the metabolism |
| What are the lizards? | The most numerous and diverse group of reptiles |
| What are the turtles? | The most distinctive group of reptiles; adapted to deserts or aquatic habitats; have a boxlike shell made of shields fused to the vertebrae, clavicles, and ribs |
| What are the birds? | Consists of about 10,000 species worldwide; archosaurs; almost every feature of their anatomy has been modified in their adaptation to flight; its most obvious adaptation for flight are its wings and feathers |
| How did birds originate? | They are a common ancestor with dinosaurs; the oldest known bird is Archaeopteryx |
| What is the Archeopteryx? | "An early bird"; originated 150 mya (Jurassic); had reptilian features like teeth, claws, and a long tail with vertebrae (backbone); had feathers, not for flight, but for insulation, camouflage, and courtship |
| Why was flight so beneficial? | Promoted the exploitation of flying insects; assisted with escaping from predators; helped with long distance migration |
| What are the Mammals (Class Mammalia)? | Have mammary gland which produce milk; hair; endothermic; diaphragm to ventilate the lungs; large brain; differentiated teeth |
| What are the major Mammalian groups? | Prototherians (egg-laying), Therians, Metatherians, and Eutherians (placental) |
| What are Protheria? | Consists of Monotremes (echidna, platypus); they lay eggs; have no nipples and produce milk from belly glands |
| What are Marsupials? | Describes embryo that are both early and complete development in the mother's marsupium (nipples) |
| What are Eutherians? | Describes complete embryonic development within the uterus, and the embryo is joined to the mother by the placenta |
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