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120 Cards in this Set
- Front
- Back
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tissues
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groups of cells that have a common structure, function, or both
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body plan
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a set of morphological and developmental traits
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radial symmetry
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animal with no front and back, or left and right
-often sessile or planktonic(drifting or weakly swimming) |
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bilateral symmetry
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two sided symmetry
-often move actively and have a central nervous system -a right and left side -a dorsal (top) side and a ventral (bottom) side -anterior (head) and posterior (tail) ends |
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cephalization
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the development of a head
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ectoderm
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germ layer covering the embryo's surface
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endoderm
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the innermost germ layer
-lines the developing digestive tube |
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archenteron
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the developing digestive tube
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diploblastic
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animals that have an ectoderm and an endoderm
-include cnidarians and comb jellies |
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triploblastic
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animals that have an ectoderm and an endoderm but also an intervening mesoderm layer
-these include all bilaterians |
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mesoderm
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forms organs between ectoderm and endoderm
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coelom
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a true body cavity
-derived from mesoderm |
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coelomates
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animals that possess a true coelom
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pseudocoelom
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a body cavity derived from the mesoderm and endoderm
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pseudocoelomate
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triploblastic animals that possess a pseoudocoelom
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grade
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a group whose members share key biological features
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Protostome Development (Cleavage, Coelom Formation, and Fate of the Blastopore
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Cleavage
-spiral and determinate Coelom Formation -the splitting of solid masses of mesoderm forms the coelom Fate of the Blastopore -the blastopore becomes the mouth |
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Deuterostome Develpoment (Cleavage, Coelom Formation, and Fate of the Blastopore)
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Cleavage
-is radial and determinate Coelom Formation -the mesoderm from the wall of the archenteron forms the coelom Fate of the Blastopore -the blastopore becomes the anus |
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blastopore
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forms during gastrulation and connects the archenteron to the exterior of the gastrula
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Parazoans
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not considered a monophyletic group
-are considered to be basal to all other animals -lack true tissues -almost all belong to Phylum Porofera -other member is Phylum Placazoa |
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Trichoplax adhaerens
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a pancake cell two layers thick
-single member of Phylum Placazoa |
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totipotent
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cells can transform to do all jobs
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pluripotent
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cells can transform to do many jobs, but not all
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Phylum Porifera
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sponges
-becoming model organisms in search for earliest hints of features that are present in more highly derived taxa -8000 extant species, 99% marine -except for larval stage, are sessile |
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Morphology of Phylum Porifera
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no obvious tissues or organs
-no gut, muscles or nerves structural support comes from spicules some sponges have spongin amoebocytes and choanocytes each sponge has one or more large openings called oscula most sponges have a mesohyl |
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spicules
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tiny hard needles
-calcareous or silicious |
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spongin
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found in some sponges, a tough collagen-protein network for support
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amoebocytes
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look like amoebae
-form the outer surface of the sponge -secrete spicules -roam through the insides carry food to other cells |
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choanocytes
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look like single choanoflagellates
-central flagellum surrounded by microvillar collar -line inside of sponge, or numerous small chambers -are numerous openings to outside of sponge that lead to central chamber |
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spongocoel
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central chamber of sponges
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mesohyl
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a gelatinuous acellular layer between the outer skin and the choanocyte layer
-sponges -because it is acellular it is not a tissue |
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Feeding of Phylum Porifera
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vast majority suspension feeders
-beating of choanocyte flagella draws water in through the ostia, through the microvillar collar, where food particles are removed, and out through the osculum -food particles are phagocytksed by base of choanocyte cell -amoebocytes nudge up and take up food passed on by choanocyte -amoebocytes then carry food to other cells, or use energy to make spicules or other structural materials |
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Reproduction in Phylum Porifera
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-some sponges have separate sexes
-others are hermaphroditic (simultaneous or sequential) -do not have ovaries and testes -eggs arise from modified amoebocytes, sperm from modified choanocytes 1) Eggs retained in mesohyl and sperm sent through oscula 2) sperm sucked in through ostia of neighbouring sponge of same species 3) zygote retained until it develops into a ciliated larva 4) larva swims out and lands on substrate, either turns inside out or external ciliated cells migrate inside 5) ciliated cells drop or reabsorb cilia, then grow flagella to become choanocytes |
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simultaneous hermaphrodites
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are male and female at the same time
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sequential hermaphrodites
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are first one sex, then change to be the other
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Indeterminate cleavage
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each cell in the early stages of cleavage retains the capacity to develop into an embryo
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polyp
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Phylum Cnidaria
-has oral end upwards, and aboral end attached to a substrate -e.g. anemone |
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medusa
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Phylum Cnidaria
-has oral end downwards and aboral up -moves freely throughout water -e.g. jellyfish |
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Class Hydrozoa
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Phylum Cnidaria
-both polyp and medusa in life cycle -polyp is sessile and often colonial (reproduces asexually by budding) -medusa budded of asexually (reproduces sexually, larva settles and transforms to polyp) |
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Class Scyphozoa
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Phlyum Cnidaria
-spend almost all their life cycle as medusa -have very thick layer of mesogloea -jellyfish -swim by contracting network of fibres around circumference of bell (not considered true muscles because not derived from embryonic mesoderm) |
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Class Cubozoa
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Phylum Cnidaria
-medusa is dominant, but is cube shaped -box jellies -have complex light and movement detecting eyes along perimeter of bell -have extremely toxic cnidocytes |
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Class Anthozoa
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Phylum Cnidaria
-are entirely polyps -some live as single individuals (sea anemones) -others are colonial (coral) |
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Phylum Ctenophra
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comb jellies, sea gooseberries
-all marine -move by beating thousands of cilia arranged in bands -like Porifera, appear to lack Hox genes -two tissue layers and a layer of mesogloea -mouth but no anus -two long tentacles covered with colloblasts that explode with glue-like substance upon impact |
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Phylum Platyhelminthes
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the flatworm
-are acoelomate -basically solid tissue -do not have special circulatory or gas-exchange system -do not have a complete digestive system -have a mouth and a gut lumen, but no anus |
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Class Turbellaria
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Phylum Platyhelminthe
-free-living flatworms -epidermis of turbellarians covered by cilia -have a pair of ventral nerve chords -a pair of ganglia near the front of the the body -no anal opening (undigested food ejected from mouth) |
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Class Cestoidea
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Phylum Platyhelminthe
-tapeworms -entirely endoparasitic in digestive systems of other animals -lack digestive system (absorb nutrients through thing body wall) -scolex modified for holding on to host's gut - after scolex comes the proglottids -new proglottids produced at base of scolex -older proglottids towards posterior of body -mature proglottids filled with eggs are defecated by host -eggs eaten by intermediate host (pigs) -intermediate host eaten by final host (humans) -larvae develop into adult tapeworm in gut of final host (parasite now engages in sexual repro) |
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scolex
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tapeworms
-front end of body modified for holding onto host's gut |
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proglottids
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tapeworms
-long chain of units devoted to reproduction |
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Phylum Brachiopoda
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lamp shells
-one of four lophophore -some are attached to substrate by a rubbery stalk -have complete gut with anal opening -suspension feed using paired lophophores |
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Phylum Ectoprocta
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-gut is U-shaped with anal opening outside of the lophophore
-almost all are colonial -colonies look superficially like coral -many species have units specialized for different tasks -some colonies are able to move |
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Phylum Annelida
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segmented worms
-segments separated by internal septa -are eucoelomate -have closed circulatory system (blood contained in vessels) -have complete digestive system with anus |
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eucoelomate
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body cavity completely lined with mesodermally derived tissues
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Class Polychaeta
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Phylum Annelida
-almost entirely marine -most body segments have fleshy lobes that bear many chaetae -have clearly differentiated head with sensory antennae and often with eyes -usually predatory -sedentary polychaetes either ingest substrate and digest organic matter, suspension feed, or deposit feed -usually dig burrows and/or construct tubes -many polychaetes free-spawning -trochophore larvae are planktonic, with subsequent leading benthic lives |
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deposit feed
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trail sticky tentacles over substrate and licking off adhering matter
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free-spawning
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-eggs and sperm released into water
-fertilization occurs outside body of female parent |
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Class Oligochaeta
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Phylum Annelida - earthworms
-lack both parapoidia and a well developed head -still have a few chateau -most feed by ingesting substrate and digesting organic matter -do not free spawn -most are simultaneous hermaphrodites and transfer sperm by copulation -undergo direct development |
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copulation
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-each worm in a pair acts as both male and female
-deposits sperm in partner's seminal receptacle, receives in its own -produces gelatinous cocoon, slides cocoon forwards and deposits sperm -hence fertilization is still external |
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Class Hirudinea
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Phylum Annelida - leeches
-lack parapoidia, have clitellum -lack chateau -most predators very stealthy |
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Phylum Mollusca (characteristics)
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snails, clams, squids, and many others
-most marine Characteristics -calcareous shell secreted by thin layer called mantle -muscular ventral foot used for movement -organs contained in a visceral mass above foot -radula -gills for gas exchange and sometimes feeding -open circulatory system (blood not in vessels, coelom reduced) -not clearly segmented -many with trochophore |
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Class Gastropoda
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Phylum Mollusca - snails
-glide along using muscular contractions of large foot -most have single, coiled, tubular shell -slugs are those that have lost shells -shell species undergo torsion -most gastropods are grazers, scrape algae off substrates using radula -protected by nematocysts of cnidarians |
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torsion
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visceral mass twists during development so that anal opening over head
-snails |
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nudibranchs
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shell-less marine gastropods
-sea slugs |
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Class Bivalvia
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Phylum Mollusca - clams, oysters, scallops
-have two hinged shells -feed by filtering water through gills -no radula (do not really have a head) -some are essentially sessile but most are sedentary and can move if necessary (scallops swim by clapping their valves) |
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Class Cephalopoda
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Phylum Mollusca - squids, cuttlefish, octopuses
-have many long tentacles arranged around mouth -tentacles have suckers and/or hooks -are all predatory; have radula modified as biting beak (often have poison) -most spp. have no evidence of external shell (excepting being nautiluses and extinct ammonites) -have tube of mantle to make siphon (used for jet propulsion) -only molluscs to have closed circulatory system -squids attach eggs to substrate -octopuses show maternal care -do not have trochophore larvae -direct development |
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ecdysis
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when entire cuticle is shed at once
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cuticle
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non-living outer layer of skin
-made of 3 layers 1) endocuticle - within 2) exocuticle - outside 3) epicuticle - a layer of waxes |
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epidermis
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below cuticle, living cells that secrete substances that become cuticle
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Moulting
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1) apolysis
2) inactive moulting fluid is secreted by the epidermis 3) a thin, protective layer is deposited between moulting fluid and epidermis 4) enzymes in the moulting fluid are activated, endocuticle is digested -liquefied products taken up by epidermis -sclerotized exocuticle not digested 5) a new undifferentiated layer of cuticle deposited beneath protective layer -greater surface area of new cuticle created than is in old cuticle 6) moulting fluid reabsorbed 7) epicuticle (wax layer) laid down 8) old exocuticle and epicuticle moulted 9) new cuticle expanded 10) outside of new cuticle sclerotized by secretions transported through canals |
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apolysis
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the epidermis separates from the endocuticle
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Phylum Onychophora (Morphology)
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velvet worms
-soft-bodied -segmented -lobopods Morphology -little cephalization -open circulatory system -coelom becomes reduced to pockets around gonads during embryonic development -exchange gases using a tracheal system |
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lobopods
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many pairs of unjointed legs tipped with claws
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tracheal system
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openings on the side of the body (stigmata or spiracles)
-lead to large-bore tubes (tracheae) -which terminate in many fine tubes (tracheoles) -oxygen diffuses through thin tracheal walls into tissues, carbon dioxide diffuses out into tracheoles |
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Phylum Onychophora Ecology
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all are predators
-capture prey by shooting glue from glue glands next to mouth have separate sexes (dioecious) normal copulation and hypodermic insemination |
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hypodermic insemination
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spermatophore placed on female's skin, digests through into haemocoel, sperm released and crawl to eggs
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oviparous
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ovi=egg, pareo=to give birth
-lay eggs that undergo embryonic development outside female's body |
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ovoviviparous
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viv=alive
-eggs retained in the mother's body where the young developed, nourished by yolk, and hatch inside the mother |
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viviparous
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young undergo development inside mother where they receive nutrients via a placental connection to mother's tissues
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Phylum Tardigrada
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water bears
-have 4 paris of claw-tipped lobopod limbs -move by stepping slowly -no antennae -no gas exchange system (small enough that whole body acts a gill) -moss and soil dwelling species are able to enter state of suspended animation in response to drying of habitat -can withstand desiccation and freezing |
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Phylum Nematoda
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round worms, threadworms
-no segmentation -no appendages -no eyes -do not moult -pseudocoelomate (have body cavity, but mesoderm does not completely line it) -most nematodes have two sexes -direct development -eutelic -many parasites |
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eutelic
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post-embryonic growth occurs by each cell growing, not by addition of cells
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Phylum Arthropoda (characteristics)
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most species rich phylum of any organism (1 million extant, named species)
-have jointed limbs -have a sclerotized cuticle made of chitin that acts as an exoskeleton -have segmented bodies -most are well cephalized -most have other tagmata as well as head |
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tagma
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collection of adjacent segments specialized for some function
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Main groups of Arthropods
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1) Trilobita
-trilobites, all extinct 2) Chelicerata -scorpions, spiders, mites 3) Myriapoda -millipeds, centipedes 4) Crustacea -crabs, lobsters 5) Hexapoda -springtails, insects |
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Chelicerates
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-most marine cheliceriforms are extinct
-most modern chelicerifroms are arachnids |
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chelicerae
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clawlike feeding appendages
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Arachnids
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Chelicerates - spiders, scorpions, ticks, and mites
-have an abdomen and a cephalothorax, which has six pairs of appendages: the chelicerae, the pedipalps and four pairs of walking legs -gas exchange in spiders occurs in book lung -many spiders produce silk, a liquid protein, from specialized abdominal glands |
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Myriapods
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millipedes and centipedes
-millipedes eat decaying leaves and plant matter -have many legs, with two pairs per trunk segment -centipedes are carnivores -have one pair of legs per trunk segment |
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Hexapoda
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insects
-flight is one key to great success of insects (can escape predators, find food, travel to new habitats fast) -many insects undergo metamorphosis during their development |
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complete metamorphosis
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larval stages known by such names as maggots, grubs, or caterpillars
-looks entirely different from the adult stage |
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incomplete metamorphosis
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the young (nymphs) resemble adults but are smaller and go through a series of molts until they reach full size
-e.g. grasshoppers |
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Crustaceans
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-found in marine and freshwater environments
-branched appendages specialized for feeding and locomotion -small crustaceans exchange gases through the cuticle, larger ones have gills -most have separate male and female |
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Decapods
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relatively large crustaceans and include lobsters, crayfish, and shrimp
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Isopods
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include terrestrial, freshwater, and marine species of crustaceans
-e.g. pillbugs |
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Echinoderms (Phylum Echinodermata)
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sea stars and sea urchins
-slow-moving or sessile marine animals -a thin epidermis covers an endoskeleton of hard calcareous plates -most adults have radial symmetry with multiples of five (larvae have bilateral symmetry) -have a unique water vascular system, a network of hydraulic canals branching into tube feet that function in locomotion -most males and females are separate |
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Asteroidea
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Phylum Echinodermata - sea stars and sea daisies
Sea stars -have multiple arms radiating from central disk -undersurface of arms bear tube feet, which grip substrate with adhesive chemicals -can regrow lost arms -feed on bivalves by prying them open with their tube feet, everting their stomach, and digesting their prey externally with digestive enzymes Sea daisies -live on submerged wood and absorb nutrients through a membrane that surrounds their body |
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Ophiuroidea
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Phylum Echinodermata - brittle stars
-have a central disk and long, flexible arms which they use for movement -some are suspension feeders, while others are predators or scavengers |
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Echinoidea
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Phylum Echinodermata - sea urchins and sand dollars
-no arms but five rows of tube feet -their spines are used for locomotion and protection -sea urchins feed on seaweed using a jaw-like structure on their underside |
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Crinoidea
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Phylum Echinodermata - sea lilies and feather stars
-sea lilies live attached to a substrate by a stalk -feather stars can crawl using long, flexible arms -both are suspension feeders |
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Holothuroidea
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Phylum Echinodermata - sea cucumbers
-lack spines, have reduced endoskeleton -sea cucumbers have five rows of tube feet; some of these are developed as feeding tentacles |
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Phylum Chordata
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-bilaterian animals
-belong to the clade of animals known as Deuterostomes -comprise all groups of vertebrates -and two invertebrates (the urochordates, the cephalochordates) |
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Notochord
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-a longitudinal, flexible rod between the digestive tube and nerve chord
-provides skeletal support throughout most of the length of a chordate |
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Dorsal, Hollow Nerve Cord
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-the nerve cord of a chordate embryo develops from a plate of ectoderm that rolls into a tube dorsal to the notochord
-the nerve cord develops into the central nervous system: the brain and the spinal cord |
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Pharyngeal Slits or Clefts
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-are present in most chordates
-develop into slits that open to the outside of the body -suspension feeding structures in many invertebrates chordates -gas exchange in vertebrates (except vertebrates with limbs) -develops into parts of the ear, head, and next in tetrapods |
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Muscular, Post-Anal Tail
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-chordates have a tail posterior to the anus
-in many species, the tail is greatly reduced during embryonic development -the tail contains skeletal elements -provides propelling force in many aquatic species |
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Lancelets (Cephalochordata)
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Invertebrate Chordate
-bladelike shape -marine suspension feeders that retain characteristics of the chordate body plan as adults |
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Tunicates
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Invertebrate Chordate
-are more closely related to other chordates than lancelets -most resemble chordates during their larval stage -as an adult, tunicate draws in water through an incurrent siphon, filtering food particles -when attacked shoot water through their excurrent siphon |
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Craniates
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chordates that have a head
-two clusters of Hox genes -neural crest -in aquatic craniates, the pharyngeal clefts evolved into gill slits -have a higher metabolism and are more muscular -have a heart with at least two chambers, red blood cells with hemoglobin, and kidneys |
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neural crest
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Craniates
-a collection of cells near the dorsal margins of the closing neural tube in an embryo |
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Hagfishes
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Myxini
-a cartilaginous skull and axial rod of cartilage derived from the notochord -lack jaws and vertebrae -have a small brain, eyes, ears, and tooth-like formations -marine, bottom-dwelling scavengers |
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Gnathostome vertebrates
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jawed fish
-2 pairs of fins -extinct agnathans had at most 1 pair -extant agnathans have no paired fins -bigger brain (smell & vision) -extant gnathostomes have 4 clusters of Hox genes |
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Evolution of jaws?
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modifications of 2 pairs of skeletal rods that had supported anterior pharyngeal slits
-with jaws, more ways of getting food than suspension feeding using pharynx -posterior slits become specialized for gas exchange (gill slits) |
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Chondrichthyans
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Sharks, Rays and their relatives
-endoskeleton made of cartilage -bony teeth |
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Sharks
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-main swimming propulsion comes from tail (pectoral fins add lift)
-do not have gas-filled swim bladder -gain buoyancy by storing oil in liver (sink when not swimming) -when resting on bottom, must gulp water to aerate gills -teeth appear to be homologous to the jagged scales that make shark skin feel so rough -shark teeth continuously replaced -can detect changes in electrical fields generated by muscular movement (via pores around head) -can detect vibrations in water (via lateral line) -sperm transfer through copulation -fertilization internal -some species, oviparous, others ovoviviparous or viviparous -cloaca |
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cloaca
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found in sharks
-reproductive tract, excretory system(urine), and digestive tract(feces) all exit through same opening |
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Conondonts
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first vertebrates with mineralized skeletal elements in their mouth
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Characteristics of Bony Fish
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-have ossified skeleton
-have flat plate-like bony scales -gill openings covered by single protective flap (operculum) -swim bladder -flexible fins -external fertilization common |
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swim bladder
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air sac that controls buoyancy of fish
-gas exchange between blood and bladder changes degree of inflation of bladder |
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Class Actinopterygi
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ray-finned fishes
-both marine and freshwater -named for long flexible rays that supports fins |
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Class Actinistia
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lobe-finned fishes
-only one extant genus of actinistians (the coelacanth) -have fleshy, muscular pectoral and pelvic fins supported by bony elements in the base |
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Class Dipnoi
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lungfishes
-3 extant genera, restricted to freshwater habitats in southern habitats -have gills and lungs -gulp air into lungs from water's surface by lowering and raising floor of mouth cavity (buccal pump) -can survive dry periods by burying themselves in mud |
