Exam 4 Flashcards
Animals are…
Heterotrophic, multicellular, and have tissues
What are tissues?
Layers of cells that act as a functional unit
During cleavage there is rapid ____ but no ____
division; cell growth
There is no cell growth during cleavage because…
The cells are dividing so quickly that there is no time for the cell to grow
Steps of creating and embryonic layer
Zygote –> cleavage –> eight cell stage –> cleavage –> blastula –> gastrulation (becomes a gastrula)
Blastocoel
The hallow inside of a blastula
What is Gastrulation?
When the embryo folds inward, expands and fills in the blastocoel. Germ layers form through gastrulation.
Ectoderm
Outer layer of an animal
Endoderm
Inner layer of an animal that can make up the inside of the digestive tract
Archenteron
The hallow space inside the endoderm
Animals origin
750 million years ago
Animals closest relative are ___ because…
Choanoflagellates; their genetic similarity and behavioral similarities such as signaling and adhesion
Sponges lack
True tissues
___ of sponges have been found in other animals but not plants, fungi, or non-choanoflagellates
Collar cells
Proterozoic Era
1 billion - 542 million years ago; Ediacaran Period (560 mya)
Paleozoic Era
541 - 242 mya; Cambrian Period (525 mya)
During the Cambrian period, there is rapid diversification of ____
Bilaterians
450 mya
Arthropods are discovered
365 mya
Vertebrates colonize
Radial symmetry
has a top & bottom, but no left/right or front/back
Bilateral symmetry
Has a top/bottom and a left/right
Ectoderm
Germ layer on the outside surface embryo; for some phyla the ectoderm can form the central nervous system
Endoderm
Inner germ layer that lines the archenteron and gives rise to the lining of the digestive tract
Diploblastic
Two germ layer (the endoderm and ectoderm); cnidarians
Triploblastic
Three germ layer (endoderm, ectoderm, mesoderm); all bilaterians
Mesoderm
Forms muscles and other internal organs
Coelom
A fluid or air-filled space located between the digestive tract (endoderm) and outer body wall
Acoelomate
Lack internal body cavity
Coelomate
Have an internal body cavity with the inside and outside by mesoderm-derive tissues
Pesudocoelomate
Have an internal body cavity with the outside surrounded by mesoderm and the inside derived by endoderm
Spiral and determinate cleavage
Seen in protostomes; where spiral division is diagonal to the vertical axis and determinate development casts the developmental fate of each embryonic cell very early
Radial and indeterminate cleavage
Seen in deuterostomes; where radial has parallel or perpendicular cell division and indeterminate development early cleavage divisions retain capacity to develop into a complete embryo
In a protostome the ___ develops where as in a deuterstome the ___ develops
mouth; anus
Basal eumetozoas are
Cnidara and Ctenophora and are diploblastic with radial symmetry
Eumetozoas have…
True tissues
Bilateria clades
Deuterostomia, lophotrochoza, and ecdysozoa
Bilateria exhbibit ___ symmetry and have ___ germ layers
radial; 3
Porifera
lack true tissues; part of the metazoa (basal); asymmetric, choanocytes flap to swirl water and catch food; parasitic/free-living; have a radula; have a gastrovascular cavity
Cnideria
Diploblastic; exhibit radial symmetry; cnidocytes (tentacles) grab prey; medusa/polyp body forms which have a single opening that functions both as a mouth and anus; have gastrovascular cavity
Platyhelminthes
Free-living and parasitic; triploblastic and bilateral symmetry; acoelomates; dorsoventrally flattened; no digestive tract, instead they exchange gases within the gastrovascular cavity
Tapeworms
No mouth/gastrovascular cavity; they rely on hosts digestion tract to absorb nutrients
Ctenophora
When prey attack, cells burst open and cover prey with sticky threads
Rotifera
Triploblastic; bilateral symmetry; pseudocoelomate; have a cllia that draw vortex of water into mouth and trophi grind up food; possess an alimentary canal that has a digestive tube with a mouth and anus
Ectoprocta/Brachiopoda
Triploblastic; bilateral symmetry; coelomates; possess lophophores: ciliated tentacles that carry food to cilia then to digestive system
Mollusca
Triploblastic; bilateral symmetry; coelomates; have a radula (break down food for digestion); have a muscular foot (movement), mantle (shell) , and visceral mass (organs)
Gastropods
land snails, sea slugs and chiton (flat)
Bivalves
Clams and oysters
Cephalopods
squids, octopus, and chambered nautilus
Annelida
segmented worms; triploblastic; bilateral symmetry; coelomates; parasitic/free-living
Errantia
clade of annelida that is mobile and marine; parapodia is the structure it has used for locomotion
Sedentaria
clade of annelidea that is less mobile and found in soil; examples are leeches and earthworms
Leeches
Parasitic; use blade like jaws that secrete anesthetic to numb humans when they suck their blood; they also secrete hirudin which prevents host’s blood from solidifying
Nematoda
Triploblastic; bilateral symmetry; psuedocoelomates; free-living/parasitic; alimentary canal; undergo ecdysis (molting of their exoskeleton)
Arthropoda
Triploblastic; bilateral symmetry; coelomate; hard exoskeleton (chitin), segmented body (head, thorax, abdomen), and joined appendages
Three lineages of arthropoda
Chelice rates (spiders, scorpions), myriapods (centi and milipedes), and pancrustaceans (insects)
Incomplete metamorphosis
nymphs (young) are smaller, have different body proportions, and lack wings; as they molt, they look more like an adult where their final molt is full size, with wings, and sexually mature
Complete metamorphosis
Larval stages are for eating and growing (caterpillar) and the adult (pupal) stage is for reproducing and dispersal; larval stage looks completely different from adult stage
Hemichordates
have a notochord, nerve chord, gill slits, and dorsal nerve chord
Echinodermata
have a water vascular system; larvae are bilaterally symmetrical and adults are radially symmetrical
Chordates developed the ____
notochord
Vertebrates developed the ___
vertebrae
Gnathostomes developed the ___
jaws
Osteichyans developed the ___
lungs
Lobe-fins developed the ___
lobed fins
Tetrapods developed ___
limbs with digits
Amniotes developed ___
amniotic egg
Mammals developed ___
milk
Cephalochordata
Most basal chordate; also known as lancelets; have somites (segmented muscles from blocks of mesoderm); lack a full brain (instead they have a nerval cord with a swollen tip–>precursor of the brain)
Urochordates
Also known as tunicates; chordate characteristics are seen in the larval stage (notochord, nerve cord, and tail)
4 characteristics to make a species a chordate
dosal, hollow nerve cord; notochord; post-anal tail; pharyngeal slits/clefts
Vertebrates
Chordate that has skull and backbone; two sets of hox genes and a complete nervous system; haikoulla (eyes and brain) and myilokunmingia (head) are precursors from the cambrian explosion
First vertebrae fossil
conodonts (500 mya) with mineralized dental tissue and a cartilage as an internal skeleton; body first mineralized in the mouth then incorporated as protective armor
Vertebrates without jaws
hagfish and lampreys
Gnathostomes
evolved from the skeletal rods that previously supported the anterior pharyngeal gill slits; gill slits are needed for respiratory gas exchange; now there are four sets of hox genes; lateral line system –> sense vibrations in the water; enlarged brain (better sensory abilities)
Osteichthyans
Possess lungs (or swim bladders) for breathing
ray-finned fish
bony fish with thin fins that aid in swimming; seahorses, lionfish, and eel
lobe-finned fish
possess rod-shaped bones surrounded by a thick layer of muscle in the pelvic and pectoral fins; devonian period from 400 mya; coelacanths and lungfish
Tetrapods
in place of fins, they have limbs with digits (support weight on land; muscle-generated forces are distributed); head is separated from the body by a neck; adults lack gills (terrestrial)
Tiktaalik
Fossil that shows the first tetrapod features present (375 million years ago); neck, ;ribs, fin skeleton, flat skull, eyes on top of the skull; show the transition before limbs with digits
Amphibians
Basal tetrapods that have a reproductive environment tied to water; frogs and salamanders
Frogs
At the larval stage, they are tadpoles that share similar characteristics as a fish (gills, lateral line system, long, finned tail); through metamorphosis, gills and lateral line system disappear, the the legs, lungs and digestive system adapt to a carnivores diet
Amniotes
have the amniotic egg that help future generations develop without the presence of water
Amniotic Egg Membranes + Functions
Amnion (protect embryo in a fluid filled cushion against mechanical shock); allantois (disposal sac for metabolic waste since there is no water present); chorion (exchanges gases between the embryo and the air as respiration); yolk sac (stockpile of nutrients with additional nutrients in the albumen)
With these structures, an embryo can…
develop on land in its own private bond which reduces the dependence of tetrapods on an aqueous environment; key innovation for terrestrial life
Mammals
Mammary glands produce milk for the offspring that is rich in fats, sugars, vitamins and minerals that are key for a nutritious diet; hair and fat are used for thermoregulation; heterodonty suits the diverse diet mammals have
During the ____ period, first true mammals arose and began to diversify
Jurrasic (200-145 mya)
During the ___ period, major mammal lineages appeared: the ____, ____, and ____
Cretaceous (140 mya); monotremes (lay eggs), marsupials (mammals with a pouch), and eutherians (placental mammals)
Marsupials
Born before amniotic development is complete; completed during nursing with a maternal pouch
embryo development for masrupials and eutherians
embryo develops in the uterus; this is a modification for the amniotic egg membranes because of the placenta that transports the nutrients from the mother to the baby; the placenta is formed with the uterus and the extra-embryonic layers
Convergent evolution with marsupials and eutherians
seen in similar ecological environments around the world
