Bilateria Flashcards

Question

What are the features of the pycnogondia -as class within the chilicerata which is a group of the arthropods- (a phyla within ecdysozoa, which is a group within the protostomes)?

Answer 1

Sea spiders or pycnogonids 1300 species Marine Up to 70cm leg span Mouth on a proboscis which extends down from body Mostly carnivorous on sessile and feed on soft bodied invertebrates Caecae of midgut protude down legs, provides extra surface area for digestion Narrow prosoma- 4-6 pairs of legs, ovigers- modified legs used for grooming and for carrying eggs Vestigial opisthosoma No organs for gas exchange

Answer 2

Class is merostomata, order is xiphosura Horseshoe crabs 4 species Costal waters Prosoma covered by large dorsal shield 5-6 pairs of respiratory appendages on opisthosoma- book gills Well developed spine (telson) Pair of compound eyes and pair of simple eyes

Answer 3

Arachnids Unsegmented prosoma, typically with solid carapace Have chelicerae and pedipalps 4 pairs of legs Opisthosoma lacks appendages, often heavily modified Carnivorous Sensory hairs, eye, slit sense organs (detect air pressure) Scorpiones: Scorpions 1750 species Prosoma- chelate pedipalps (claws), single shield covers whole prosoma Opisthosoma- mesosoma of 7 broad segments, metasoma of 5 narrow segments, telson modified into venom gland and sting Neurotoxic and painful venom, strong venom usually means they have weak pedipalps Opiliones: Harvestmen 6650 described species All habitats Omnivorous Undivided prosoma 9 segmented opisthosoma Long leg like pedipalps Single pair of simple eyes in middle of prosoma Puedoscorpiones: Book scorpions 3300 described species All habitats Less than 8 mm Claw like pedipalps with venom glands Chelicerae have silk glands 0-2 pairs of simple eyes Flattened opisthosoma Phoresy- use leg to grab other organisms Solifugae: Camel spiders, sun spiders, wind scorpions 1000 species Desert biome Predatory on large invertebrates and small invertebrates Large prosomal shield Two jointed chelicerae, no venom Leg like adhesive pedipalps Thelyphondia: Whip scorpions, vinegaroons, uropygids 100 species Pedipalps have crushing jaw Elongated 1 st legs used as sensory appendages Telson tail is sensory organ particularly detecting movement and air pressure Acetic acid as defence mechanism Amblypygi: Whip spiders, tailess whip scorpions 160 species Pedipalps are raptorial Elongated 1 st legs used as sensory appendages Aranae: True spders Prosomal segments fused Opisthosoma of 12 segments attached with narrow stalk Jointed chelicerae with venom glands Leg like pedipalps for food handling and insemination Up to 8 eyes Silk glands 45700 described species All habitats All but one species is predatory Divides into three sub classes: mesothelial (1 species), opisthothelae (mygalomorphae, araneomorphae), -Mygalomorphae: Heavily built and hairy Robust chelicerae that move up and down Reduced spinnerets Main groups are the tarantulas, trapdoor spiders, funnel web spiders -Aranemorphae: 90% of all spiders Chelicerae move laterally/side to side Acri: Mites and ticks 50000 species Fusion od prosoma and opisthoma A capitulum formed from pedipalps and chelicerae Divided into 3 main groups- oplioacariformes (similar to harvestman), acariformes (house dust mites, mange mites, feather mites, spider mites, gall mites, chiggers), parasiticides (hard ticks, soft ticks)

Answer 4

Myriapods Can be divided into 4 classes: Symphyla Pauropoda Diplopoda Chilopoda Classic arthropod body plan Segmented body with unbranched appendages on each segment Head composed of 5 sets of limbs- antennae, labrum, mandibles, maxilae x2 Mouth parts on under side of the head Tracheal system Spiracles on each segment Non closable spiracles May have tracheal lungs- bunches of tracheal tubes Food is chewed or scraped using mandibles External digestion in some centipedes Excrete ammonia using malphigian tubules May be egg brooders- female protects eggs until hatched Juveniles may hatch with few segments, and add additional pairs of legs whenever they moult Chief sense is touch Simple eyes (oceli), compound eyes in some centipedes, or eyeless Organs of tomosvary found at base of antennae in some centipedes. They detect vibration and changes in humidity Reproduction: Indirect sperm transmission/ no fertilisation Mating dance where both sexes palpate each others posteriors with antennae Male then produces a spermatophore Male millipedes have legs modified into gonopods that transfer sperm during copulation

Answer 5

Symphylans, pseudocenripedes 200 species Herbivores First maxilla has no palp 12 trunk segments- collum: first trunk segment no legs, gonopore: 4th trunk segment

Answer 6

Pauropods 830 species Detritivores Found in soil and leaf litter Branched antennae No eyes 11 trunk segments- collum: first trunk segment no legs, gonopore: 3rd trunk segment No trachea, they respire directly by diffusion across the body wall

Answer 7

Millipedes Short antennae Variable trunk segments- hatch with only 4 trunk segments, diplosomites: pairs of segments fused together, gonopore: on 2nd trunk segment Repugant exudate which can include hydrogencyanide, can cause blisters

Answer 8

Centipedes 8000 species Wide range of terrestrial habitats Limbs on 1st body segment modified into maxilliped which are used as claws and mouthparts Long antennae Mandibles retractable into head pouch Variable number of trunk segments- 15 or more, gonopore: on last trunk segment Forcipules, venom claws Predatory Small species are entomophagous (eat mostly insects) Larger species feed on vertebrates- lizards, rodents, birds, bats, amphibians

Answer 9

Made up of the myriapoda and pancrustacea Mandibles to process their food Antennae 3 distinct body regions

Answer 10

More than 70000 species Mostly marine, with some freshwater and terrestrial species Dominant in plankton Sessile and mobile forms Paraphyletic Cephalon (head) -mads of 5 segments -compound eyes -joined bigamous antennae -may have cephalothorax with a cepahalic shield or carapace Pereon (thorax) -part of the thorax not incorporated into the chephalothroax Pleon(abdomen) -pleopods (the abdominal limbs) Gas exchange -distinct gills, requiring constant flow of water -many decapods have branchial chambers which are between carapace and body wall. They protect gills and provide a ventilating current. Keel the gills moist in intertidal and terrestrial species Feeding -suspension feeders -filter feeders -deposit feeders -predators Reproduction -dioecious (separate sexes) -copulation and internal fertilisation -eggs brooding Development -characteristic nauplius larvae

Answer 11

Crabs, lobsters, amphipods, isopods Three body segments -head with two pairs of antennae, first pair branched -first 3 thoracic segments form cephalothorax, appendages are maxillipeds (accessory mouthparts) -abdomen with appendages Digestive system -straight digestive tract -gastric mill

Answer 12

Copepods Dominant in marine plankton No carapace 3 highly abundant orders: -calanoida -harpacticoida -cyclopoida

Answer 13

Barnacles Adults are sessile or parasitic Body has thorax and reduced abdomen No carapace in adult form Hermaphrodites Prey capture by cirri which are modified thoracic legs Attached by antennules

Answer 14

The process whereby a decapod crustacean evolves a crab like body form where: -the carapace is flatter than broad and has lateral margins -the sternites are fused into a plastron -the pleon (abdomen) is flattened and strongly bent to cover the plastron -the uropods (tail appendages) are reduced or absent

Answer 15

Fairy shrimps, water fleas, clam shrimps Most live in freshwater and brackish water Compound eyes Carapace which may consist of two valves enclosing trunk. This prevents use of limbs doe swimming, uses antennae instead

Answer 16

Entognatha Ectognatha

Answer 17

Six legs Not insects Wingless Mouthparts retract into head All antenatal segments have muscle Groups: Protura- no antennae,, non contractile heart Diplura- long antennae, no eyes Collembola- furcula (spring), collophore (water regulation)

Answer 18

Hexapod arthropods with external mouthparts and unbranched appendages Three body parts- head, thorax, abdomen Head has 5 sets of appendages Thoras has 3 pairs of walking legs Two wingless taxa (archaeognatha, zygentoma) One winged taxa (pterygota) -basal feature- lack ability to fold wings -divided ephemeroptera, odonata, neoptera -neoptera- the insects that can flex their wings over their abdomen. Have three sub groups polyneoptera, holometabola, paraneoptera - polyneoptera- generalist feeders with unspecialised biting mouthparts, incomplete metamorphosis - paraneoptera- specialist mostly liquid feeders, incomplete metamorphosis - holometabola- complete metamorphosis Body plan -head (6 segments)- procephalon: antennae and eyes, gnathocephalon: mouthparts- labrum, mandibles, maxillae, labium -thorax (3 segments)- prothorax (legs), mesothorax (legs and wings), metathorax (legs and wings) -abdomen (11 segments)- may have rudimentary segments called styli, may have terminal cerci, may have copulatory segments Respiration -tracheal system -spiracles can be open and close Circulation -circulation of nutrients no respiratory pigments via the dorsal heart Reproduction -mating stimulus induces female receptivity- odour, sound, and colour signals -internal fertilisation -females mates once or a few times in her life, stores sperm Development -incomplete metamorphism (direct/exopterygote) -complete metamorphism (indirect/endopterygote)- larvae form looks unlike the adult Ecology -1 million species -over one third are beatles -herbivores

Answer 19

Jaw bearers Complex jaws made of chitin Anus opens on dorsal side of animal No larval stage

Answer 20

Arrow worms 120 species Marine habitats Predatory feed on plankton Dart shaped body, with distinct head, trunk and tail Covered in cuticle Two compound eyes 2-120mm Hooked spines around mouth used in prey capture Some species use tetrodotoxin to subdue prey Hermaphroditic

Answer 21

Wheel animals Free living and sessile species, some are colonial 0.1-0.5mm 2200 species Freshwater habitats Corona of cillia in filter feeding and locomotion Mastax that grinds up food Dioecious

Answer 22

Thorny headed worms Parasitic involving at least 2 hosts 1400 species Less than 5mm, one species up to 65cm Highly modified rotifers Anterior, producible proboscis with spiny, recurved hooks Parasite induced behaviour

Answer 23

Jaw worms 100 species Slender thread like worms Marine Less than 1mm Use cilia to slide through mud and sand No circulation or respiratory system Cuticular jaws with strong muscles Transient anus- only forms during defecation

Answer 24

Flatworms No body cavity No transport system for nutrients, respiratory gases or waste products Blind ended digestive system Free living Turbellaria -4500 species -madine, freshwater, terrestrial (humid environments) -mostly free living predators -some are symbiotic or parasitic -lack cuticle, have an external cell layer with multiple cillia -mostly hermaphroditic Trematoda -flukes -18,000-24000 species -internal parasites of molluscs and invertebrates -complex life cycle -two suckers, one close to mouth, one on underside -muscular pumping pharnyx connecting to blind ending caeca -most famous are liver flukes Cercimeromorpha -two major grouos- monogenea and Cestoda -monogenea- 1100 species, external parasites mostly of fish, direct cycle, no intermediate hosts, no respiratory + circulatory + skeletal system, posterior wicker usuallu most developed -cestoda- 6000 species, tapeworms, largest grows to 30m, vertebrate parasites, no gut or mouth, direct absorption from host, scolex (grasping head), made up of segments called peoglottids which are detachable and filled with eggs

Answer 25

Hairy backs 790 species Microscopic, less than 3mm Live on and between marine sediments Adhesive glands, move via cillia Hermaphrodites, or parthenogenetic in freshwater species

Answer 26

Brachiopoda Phoronida Entoprocta Ectoprocta

Answer 27

Lophophore- circular U shaped ridge around the mouth with 1-2 rows of ciliated tentacles. For food collection and gas exchange Sessile as adults Plankton feeders U shaped gut. Anus close to mouth but outside lophophore

Answer 28

Horseshoe worms Marine 20 species Live within secreted tube of chitin Filter feeders

Answer 29

150 species Sessile Marine Goblet shaped body on long stalk Colonial Clones by budding Anus located within lophophore Hermaphrodites or dioecious species

Answer 30

Moss animals 4000 species Live within secreted house Anus outside lophophore Colonial organisms- formed by asexual budding Some have exoskeletons Sexual reproduction to produce new colony

Answer 31

Lamp shells 335 species Dorsal and ventral valves Filter feeders, using lophophore within shell 26,000 fossil species

Answer 32

Cycliophora Annelida Mollusca Nemertea

Answer 33

Symbiotic on the mouthparts of cold water lobsters About 0.5mm long Ring of cillia take food into U shaped digestive tract Asexual feeding adult- reproduces by budding a pandora larva which develops into another feeding adult. Can also produce a female which forms inside the adult. Can also produce a Prometheus larva which attaches to feeding adult and then produces 2-3 dwarf males inside itself. Fertilised female turns itself into a cyst containing fertilised egg. Hatches into swimming stage which then colonises a new lobster

Answer 34

Ribbon worms 900 species Carnivorous Free living Unsegmented body, no coelom (body cavity) Locomotion- ciliated gliding and muscular crawling. Also swim Dioecious with internal or external fertilisation or hermaphroditic Reversible proboscis (rhynchocoel)- used in prey capture

Answer 35

Segmented worms Each segment has repetition of internal organs Chitinous setae (bristles) Main groups -polychaeta- bristle worms -chitellata- earthworms and leeches -echiura- spoon worms -sipuncula- peanut worms Body plan: Outer epidermis Well developed segmentally arranged muscle layers- outer circular muscles, inner longitudinal muscles, with the coloem forms the hydrostatic skeleton Head made up of 2 segments Trunk made up of several thoracic segments Cheatae- chitinous bristle secreted by a specialist cell Parapodia- unjointed paired extensions of the body wall Cephalic appendages- palps used in feeding and sensation of touch, as well as filter feeding. Cirri or tentacles. Pharnyx is eversible often with jaws and teeth. Metanerism- body divided into segments and divided by septa, lined with peritoneum. Circulation: Closed circulation Pair of body cavities in each segment Dorsal vessel where blood flows anteriorly Ventral vessel where blood flows posteriorly Respiratory pigment- haemoglobin (red), chlorocrurin (green) Locomotion: Errant forms- walking or swimming using parapodia, crawling using peristalsis Boring form- burrow Sedentary- tube dwelling Feeding: Predators and scavengers Eversible proboscis grabs food. Tears food up and retracts into head Some are deposit feeders- often use palps to find organic particles Some are suspension feeders- palps covered in cillia which are used in prey capture Some are parasites- derive food from their hosts Reproduction: Dioecious with external fertilisation or internal fertilisation Some hermaphroditic Some asexual- divide into two pieces, budding off a new individual

Answer 36

Muscular foot Seven classes Mantle that secretes shell 100000 species Three characteristics- foot, visceral mass, mantle Foot: Large muscular structure that is both locomotive and supports the internal organs Modified to form the arms and tentacles in squid and octopus Contains pair of statocysts, which are balance sensors In terrestrial molluscs, foot secretes mucus to reduce friction Visceral mass: Dorsal concentration of internal organs Defined head with eyes and cephalic tentacles Open circulatory system- large fluid filled cavities, haemocyanin as an oxygen carrier Two pairs of main nerve cords Brain surrounds oesophagus Mantle: A cold of tissue covering the visceral mass Forms a mantle cavity- contains anus, hind most pair of gills, openings of the nephridia and gonads, and chemical sensors (osphradia) Responsible for secreting calcareous skeleton from shell glands on the margin- two clacium carbonate layers bonded with conchiolin, and an organic layer/periostracum Toothed radula Main groups -gastropoda- snails, limpets, slugs -bivalvia- clams, oysters, scallops -cephalopoda- octopus, squid -polyplacophora- chitons -scaphopoda- tusk shells Feeding: Herbivores Filter feeders Radula- toothed ribbon of chitin used to scrape at food materials. Odontophore/tongue responsible for protruding and returning radula into cavity Reproduction: Sexual reproduction Dioecious or hermaphroditic External fertilisation, internal in terrestrial species Egg then trochophore larvae then veliger larva then adult

Answer 37

Deep water benthic molluscs Cylindrical worm like body plan- no shell, no foot, poorly developed head, spicules made of aragonite Can be divided into two groups: Solenogastres- live on top of sea surface (epibenthic), feed on ctenophores and cnidarians Caudofoveata- burrowers, feed on foraminifera (protists)

Answer 38

25 modern species Deep ocean Weak muscular foot, distinct head, no eyes or cephalic tentacles Extensive mantle cavity Respiratory organs, muscles and excretory pores are repeated all over their body

Answer 39

Chitons 940 species Large foot, poorly developed head, no cephalic tentacles or eyes Aesthetes- organs embedded all over shell, formed by mantle. Work together to form visual images Shell made of 8 shell plates, multiple pairs of gills Body is not segmented Marine herbivores

Answer 40

20000 species, 11 orders Body Encased within a pair of valves Foot laterally compressed, head greatly reduced, no eyes or cepahalic tentacles No radula so are suspension feeders One pair of gills Water current drawn into mantle cavity, which is formed into two siphons (inhalant and exhalant) Can be split into three groups: -Protobranchia: Nut shells Basal hinge of shell composed of small teeth Simple unfolded gills only used for respiration Large labial palps used in mucociliary deposit feeding -pteriomorphia: Muscles, scallops, pen shells, oysters Asymmetrical shell valves Paired, folded gills (lamelibranch) Suspension feeders Often have a rod to aid digestion called a crystalline style Rudimentary eyes -Heterodonta: Edible clams, cockles, Venus clams, ship worms Valves of the shell equally sized Folded gills Well developed siphons

Answer 41

77000 species, 23 orders Torsion of body Occurs in development of all gastropods in late veliger stage It is rotation of visceral mass, mantle, and shell in anti clockwise direction Two stages- rapid 90⁰ twist, slower 90⁰ turn involving tissue growth Well developed crawling foot Well defined head Single thick spirally coiled shell. Has calcareous operculum to close shell Three informal groups- Prosobranchia, opisthobranchia, pulmonata -prosobranchia Marine snails Spirally could cap shaped shell Head with tentacles and basal eyes Large muscular foot and operculum -opisthosobranchia Sea hares, sea butterflies, nudibranchs Reduction or loss of shell Reduced mantle cavity and gills, no operculum Head 1-2 pairs of tentacles Detorsion -pulmonata Terrestrial slugs and snails Pallial lung instead of gills Mantle cavity on right side of the body No operculum Internal fertilisation- gypsobelum (love dart). Introduce hormone that increases sperm survival

Answer 42

Tusk shells and tooth shells 900 species Singular, tubular shell Burrowing foot, small head without eyes or cephalic tentacles No radula or gills Deposit feeders Separate sexes

Answer 43

900 species, 5 orders No foot, instead modified into prehensile arms or tentacles. Arms have suckers along their length, tentacles have suckers just at the distal ends or no suckers at all. Muscular funnel used for jet propulsion Head with complex eyes, radula and beak Pelagic- active swimmers inside the water -Nautiliodea: Single external shell 80-90 suxkerless tentacles Paid of simple eyes Paid of gills Funnel made of two separate folds Poor swimmers -coleodia Shell reduced, internal, or absent 8-10 prehensile suckered appendages 1 pair of gills Well developed nervous system Complex eyes Funnel is a single closed tube Active swimmers Can be divided into two groups- decapodiformes (have 8 arms and two tentacles, squid + cuttlefish), octopodiformes (8 arms, octopus + vampire squid)

Answer 44

Peanut worms ~200 species Unsegmented bulbous trunk Narrow anterior introvert- can be retracted into the trunk and extended to gather food Ring of short tentacles around the mouth which help with deposit feeding

Answer 45

Bristle worms Active hunters and scavengers Eversible pharynx, enlarged cirri Can divide into 3 groups: -amphinomida Fireworms Have toxin coated chaetae Jawless -eunicida Bobbit worms Complex jaw apparatus -phyllodocida Rag worms, scale worms, sandworms Benthic and pelagic species Well developed parapodia Feed on algae Pincer jaws

Answer 46

Pogonophora, beard worms, bone worms, zombie worms Have symbiotic bacteria that can be up to 15% of worms total weight. These can block the gut. They convert inorganic hydrogen sulphide, methane, or carbon dioxide into organic matter

Answer 47

Lug worms Unselective deposit feeders Sedentary- dwell in unshaped tubes, living in anoxic sediments

Answer 48

Spoon worms 230 species Secondary loss of metamerism Live in burrows Non retractable proboscis- rolled into scoop shape when feeding Some species excrete a slime funnel which lines their body. When filled it is rolled up and eaten Detritivores

Answer 49

Spaghetti worms and trumpet worms Deposit feeders Live in small tubes built from mud or else burrow in sand Non retractable tentacles used in food capture

Answer 50

Monophyletic class Posses a clitellum- non segmented section of the body wall near the head. This is used in mating. Clitellum secretes a sac, in which the eggs are deposited. Worm then retreats from the sack leaving a cocoon Chaetae reduced or absent No parapodia, heads less well defined Prostomium and peristomium lack pronounced sensory organs Hermaphrodites -Oligochaeta: Earth worms 10000 species Can grow up to 10m No sensory appendages on head Pharyngeal pumping draw in humus Move through peristalsis -hirudinea Leeches 500 species Freshwater Dorso ventrally flattened, tapered at both ends Bodies extendable 34 body segments Suckers are anterior and posterior or just posterior Proboscis without jaws for feeding Or Non protrusible pharynx with or without jaws

Answer 51

Feather duster worms, serpulids Mostly sedentary worms Tube dwellers- made from sand and shell fragments fused with mucus Ecosystem engineers Tentacular crown used in suspension feeding No pharnyx

Answer 52

Triploblastic Radial cleavage Mesoderm comes from archenteron Blastopore becomes anus Divided into chordata and ambulacraria

Answer 53

Sea lillies, sea stars, brittle stars, sea urchins, sea cucumbers 7000 species Marine No distinct head, have oral side and aboral side of body Has endoskeleton of calcareous ossicles Pentamerous (5 sided) radial symmetry- five fields with podia (feet) alternate with five fields without feet No excretory organs Unique hydraulic water vascular system Network of fluid filled canals Water used for gas exchange, feeding, sense reception and locomotion Fluid is moved around by cillia Madreporite- sieve like structure on upper surface. Permits water to enter the system Ampullae and tube feet (podia) Dioecious Larvae are cilliated and bilaterally symetrical -Crinoidea: Sea lillies (stalked) and feather stars (unstalked) Oral surface faces upwards Simplified water vascular system, no ampullae or madreporite as sessile Suspension feeders using mucociliary arms Body attached to substrate by aboral stalk -Asteroidea: Sea stars Stellate flattened body with five basic arms Mouth downwards on the surface Madreporite and anus on aboral surface Predators, scavengers, suspension feeders, deposit feeders Evert their stomach through their mouths to digest prey as it puts enzymes directly in contact with prey -Ophiuroidea: Brittle stars and basket stars Small disked shaped flattened body with 5 articulated arms Reduced vascular system Mouth and madreporite on oral surface, no anus Predators, scavengers, suspension feeders, deposit feeders -Echinoidea: Sea urchins and sand dollars Body discoidal, secondarily billateral and lacks arms Divided into two groups - regular urchins (mouth in lower surface, anus mid aboral), irregular urchins (mouth anterior, anus posterior) Suspension feeders, detritivores, herbivores -holothuroidea: Sea cucumbers Elongated body, secondarily bilaterally symetrical, lack arms Mouth anterior, anus posterior Three sides of body face down, two face up No apparent endoskeleton, they have special form of collagen in body wall Mostly deposit feeders, some suspension feeders

Answer 54

Acorn worms and pterobranchs 100 species Body can be divided into 3 segments Prosome- it is cilliated and muscular. Used in locomotion and food collection Mesosome- mouth between prosome and mesosome Metasome- pharynx with cilliated gill slits. Open circulatory system with dorsal heart Dioecious -enteropneusta Acorn worms Elongated body up to 2.5 m in length Long proboscis Short collar with no arms or tentacles Long trunk with gill slits Neurochord present- where the dorsal dollar has invaginated Through gut Deposit and suspension feeders External fertilisation Indirect development via a tornaria larva -pterobranchia Small Colonial Sedentary tube dwellers Disc shape proboscis Collar with paired arms and tentacles Short trunk with one pair of gill slits Neurochord absent U shaped gut Ciliary mucus suspension feeders Arms and tentacles derive from mesosome Interdigitate their tentacles to form a food basket Mixed development, sometimes involving ciliated larvae Also reproduce asexually by budding

Answer 55

Lancelets, scalps, and creatures with skulls 65000 living species Divided into 3 sub phyla- cephalochordata, tunicata, vertebrata Tunicata and vertebrata fall under the olfactores 5 key features: Notochord A Halloween dorsal nerve cord Pharyngeal slits An endostyle A post anal tail A notocord is a flexible rod of glycoproteins encased in actin Mesoderm origin Primary function is muscle attachment Precursor of vertebrates Involved in signalling during development Hollow dorsal nerve cord Forms from the ectoderm In non chordates the nerve cord is solid and ventral Pharyngeal slits are Openings in the pharynx that allow water to flow via the mouth and out of the pharnyx. Used in filter feeding Pharyngeal arches become jaw bones, hyoid bone, brachial skeleton (in fish), pharyngeal jaws (in fish), parts of the ear + tonsils + thymus (in tetrapods) Endostyle is an organ within the pharnyx. It assists in filter feeding by secreting mucus In some animals it is adapted into the thyroid gland Post anal tail has muscular and skeletal components Notochord and nerve cord extend into the tail Evolved primarily for propulsion In water In non chordates the digestive system runs the full length of the body

Answer 56

Lancelets Notochord extends into head 32 species Filter feeding, and buried in sand

Answer 57

Sea squirts and salps 2150 species Found in shallow water Sessile or pelagic adults Mobile larvae stages reveals chordate affinities -Appendicularia: Common planktonic organisms Transparent U shaped body with trunk and elongated tail Trunk has all organs and a midventral anus Tail contains notochord, nerve chord, and 2 muscle bands Protandrous hermaphrodites- starts with male, as they mature they become female House secreted by epithelial glands. Can be simple or complex -Ascodiacea: Sea squirts 2300 species Sessile May be solitary or colonial Filter feeders- water enters through oral siphon, through pharynx, and out through cloacal siphon No excretory or respiratory organs- take oxygen directly across body wall Tunic secreted by epithelial cells. This is their outer case. This is often pigmented -Thaliacea: Pelagic filter feeders Colonial 3 main groups- pyrosoma (brightly luminescent), salpida (barrelel shaped, form chains), dolioda (alternate sexual and asexual generations, only colonial in asexual phase)

Answer 58

Jawless vertebrates Lampreys and hagfish Recognised as a single monophyletic group called the cyclostomata Body plan: No jaws No paired fins or other limbs Notochord present in larvae and adults Seven or more paired gill pouches in pharynx Larval endostyle metamorphoses into thyroid gland Dorsal hollow nerve cord Post anal tail Ecology: Lampreys are coastal and freshwater. May migrate to freshwater to mate. Feed on live prey, mostly blood. They inject anticoagulants Hagfish are marine. Scavengers so will attack corpses of animals. Tie themselves into knots to lever scraps of food off carcasses. They can produce lots of slime, which expands in water.

Answer 59

Jawed vertebrates 2 lineages- Chondrichthyes (cartilage fish) and osteichthyes (bone fish, divided into two groups actinopterygii and sarcopterygii) Body plan: Chondrichthyes- ventral mouth, dorso-ventrally flattened body shape, exoskeleton is a dermal corset with separate placoid scales, endoskeleton is cartilaginous, caudal fin is heterocercal, pelvic fins are posterior Osteichthyes- anterior mouth, laterally flattened body shape, exoskeleton is overlapping dermal scales, endoskeleton is bony, caudal fin is homocercal or diphycercal, pelvic fins are anterior

Answer 60

Sharks, skates, rays, chimeras, dogfish Key characteristics: Loss of perichondral bone and it's replacement with stiffened cartilage In males, modification of the pelvic fins into claspers, a organ for the transfer of sperm Exoskeleton of placoid scales Respiration and circulation: 5 pairs of gill slits, first gill slits usually adapted into a spiracle behind eye Plate like gills separated by septa Ram ventilation- swim with mouth open Thermoregulation: Most are poikilothermic (unable to regulate own body temp) Behavioural Thermoregulation- move to warmer places to raise body temperature Homoeothermy found in mackerel sharks and allies May shunt warm blood into eyes and brain for better vision Digestion and excretion: Mouth central to head J shaped stomach Short intestine and spiral valve Common urinogenital aperture leads to a cloaca Nervous system: Brain- large olfactory lobes and cerebrum. Small optic lobes and cerebellum Monochromatic vision- no colour rods in eyes and are naturally far sited Sense organ ampullae of lorenzini clustered around the mouth. These are electroreceptors Reproduction: Ovoviviparous (give birth to live young) and oviparous (lay eggs) Internal fertilisation- males have pelvic fins adapted into claspers for sperm transfer Dioecious Buoyancy- rely on fatty liver to give neutral buoyancy. Up to 25% of body weight Break down into two sub classes- holocephali and elasmobranchii -holocephali: Rat fishes and elephant fishes Benthic, feed mostly on invertebrates -elasmobranchii: First group within is galeomorphi Second group is squalomorphi- lack anal fin, nictitating membrane Third group batoidea

Answer 61

Ray finned fish and lobe finned fish Key characteristics: Widespread ossification of braincase and post cranial skeleton Large dermal bones in cranium and pactoral girdle Ear contains large otoliths used for detection of linear acceleration Teeth attached to dermal bones of jaw or palate Anterior and posterior nostrils separate Respiration and circulation: 5 pairs of gill slits protected by an operculum Hair like gills Water pumped over gills- two phase action, Buccal and opercular Thermoregulation: Most poikilothermic Some can maintain muscles at higher than environmental temperature Raise temperature in brain and eye for better vision Digestion and excretion: Mouth anterior to head Variable shaped stomach Long intestine without valve Separate anus, urinary and genital apertures Nervous system and senses: Brain- small olfactory lobes and cerebrum, large optic lobes and cerebellum Colour vision and naturally near sighted Chemoreception Lateral line which detect current and vibrations Auditory sense via swim bladder Reproduction: Most are oviparous External fertilisation Dioecious Simultaneous hermaphroditism- where they are both male and female Sequential hermaphroditism- protandry (male first), protogyny (female first) Locomotion: 3 forms- angulliform (move most of the post head body), carangiform (move about half of the body), ostraciiform (inflexible body, move just tail) Buoyancy- their bodies are denser than water. Has a swim bladder -Actinopterygii: Ray finned fish Moveable premaxilla- can protrude jaws Homocercal tail with equal sized lobes Tend to be lighter and more flexible than more basal fish -sarcopterygii: Lobe finned fish Contains the tetrapods Fleshy, lobes paired fins joined to the body by a single bone- homologous to the femur Diphycercal tail Two dorsal fins with separated bases Teeth covered with true enamel 3 sub groups- actinistia, dipnoi, tetrapodomorpha Amphibious Lifestyles: Gas exchange through skin, mucus membranes in mouth (mudskippers) Labyrinth organs on gill arches (gouramies) Respire through air in digestive tract or swim bladder (minnows and carps) Lungs connected to the pharnyx without a trachea (lungfish) Locomotion- springing, undulation, tripod like walking

Answer 62

Modern day frogs, toads, newts, salamanders, and caecilians Tetrapod gnathastomes vertebrates- tetrapods are the four legged lobe finned fish Preadaptation for life on land: Lungs developed before moving onto land- outgrowths of the gut for buoyancy and oxygen supply Choanae- allow them to breathe in through nose Had adaptations for shallow water- flattened body and skull, as well as paired lobed fins for movement Fins developed a bend at elbow and knee Modified skull and jaw to grab food on land Body plan: Evolved from a salamander-like body plan Skin has cornified layer but is permeable to water- moulted in one piece, gas exchange takes place through skin, mucous glands keep skin moist, granular glands secreted distasteful or poisonous substances Respiration: Lungs are simple compared to amniotes Large alveoli, few internal walls Less efficient as oxygen diffuses slowly Use Buccal pumping rather than ribs to ventilate Undergo cuticular respiration which requires a water layer. More efficient at lower temperatures Larvae have external gills Circulation: Two chambered heart in larvae which only pumps deoxygenated blood Three chambered heart in adults, one ventricle, two atria. Some mixing of oxygenated and deoxygenated blood Digestion: Carnivorous Most catch prey with sticky tongue Inertial feeding to assist with swallowing, plus eyeballs Have large lovers which store glycogen Posses fat bodies near kidneys Excretions: Kidneys are dorsal. Filter blood with a high pressure system Excrete urea due to need to conserve water Larvae excrete ammonia Nervous system: Brain is equal parts: cerebrum, midbrain and cerebellum Pineal body controls hibernation and aestivation Operculum-plectrum complex is responsible for transmitting vibrations and sounds Papillae amphibiorum and papillae basilaris detect sound at different frequencies Larvae amphibians retain lateral line Reproduction: Requires fresh water Frogs use external fertilisation- male grasps female Salamanders and caecilians use internal fertilisation- male salamander produces a spermatophore, male caecilian uses an intromittent organ Larvae metamorphosis regulated by thyroxine and prolactin -Anura: Frogs and toads Have a urostyle Long forward slopping ileum pelvis Lower jaw without teeth Frontoparietal bone between eyes 4800 species No biological difference between frogs and toads -Urodela: Salamanders 655 species Slender bodies with blunt snouts Shirt limbs projecting at right angles Tail in both adult and larval forms Reduction of toes, amphiumas have reduced legs, sirens have no hind limbs Extreme self defence- caudal autonomy and puncturing ribs -Gymnophiona: Caecilians 200 described species Found in wet tropics Eat soil dwelling invertebrates Eyes only detect light and dark Have a pair of tentacles between eyes and nostrils Adapted to burrowing lifestyle- completely lack limbs, tail may be absent, strong skull with pointed snout, skin has ring shaped folds, scales containing calcite Most viviparous

Answer 63

Lissamphibia Amniota

Answer 64

Lizards, snakes, crocodiles, birds and mammals Tetrapod gnathastome vertebrates Can be referred to as reptiles- all tetrapods whose ancestors had an amniote egg 2 lineages- synapsida, sauropsida ( lepidosauria + archosauria) Amniote egg- water tight, allows gas exchange, copes with nitrogenous waste, extra embryonic membrane: amnion, chorion, allantois -Sauropsida: All amniotes that are descended from the last common ancestor of extant reptiles and birds Can be divided into the parareptilia and diapsida (lepidosauromorpha + archosauromorpha)

Answer 65

Divided into Lepidosauromorpha and archosauromorpha -Lepidosauromorpha: Sprawling gait- limbs stick out at angle, trunk and tail have sinusoidal movement Sliding joint in shoulder Pleurodont dentition- sides fused to inner surface of jaw Males have hemipenis Scales are keratinized structures of the epidermis, they overlap and shed collectively Caudal autotomy- can shed their tails Ichthyopterygia- extinct taxon of aquatic lepidosauromorpha A group within is the Lepidosauria: a sauropsid amniote Only living members of the lepidosauromorpha Modern tuatara, snakes and lizards Body plan- dry scaly skin with few dermal glands Paired hemipenis in eversible pouches Hooked fifth metatarsal- like a heel Fracture planes in tail to help shed their tails Respiration: lungs lack bronchioles- have simple hollow sacs with internal folds Large lizards have interconnected chambers Snakes have one working lung No diaphragm Circulation: three chambered heart- two atria and one ventricle. Mixing of oxygenated and deoxygenated blood Digestion: j shaped stomach, temperature effects speed of digestion Excretion: excrete uric acid with some ammonia and urea. Snakes have one kidney Nervous system: brain less than 1% of body mass Expanded cerebrum and cerebellum compared to amphibians Spinal cord extends to tip of tail Poor hearing Vomeronasal organ- airborne molecules transferred to Jacobson's organ Reproduction: males have hemipenis, usually inverted within their bodies. They use one at a time and alternate Oviparous (lay eggs), viviparous (give birth to live young), ovoviviparous species (eggs hatch inside body) Parthenogenetic species Two orders- rhynchocephalia and squamata with many groups within talked about below Rhynchocephalia- sister group of lizards and snakes Pineal eye- 3 eyes Acrodont teeth- fused to jaw bone. Two parallel rows of teeth in upper jaw. Gastralia (ventral ribs, lost in squamates). Squamata- kinetic mobile quadrate bone in skull which permits swallowing Some have uniform teeth, heterogeneous teeth -Archosauromorpha: The clade that includes the most recent common ancestor of living birds and crocodilians Parasagittal gait- limbs parallel to vertebral column Fenestra in front of eyes and in jaw The coding dentition- teeth in sockets Males have a penis Scutes made of dermis, may have bony components, non overlapping and shed in flakes Cannot shed tails Has fourth trochanter- knob on femur where retractor muscle for tail attaches which facilitates a bipedal gate Sauropterygia: extinct taxon of aquatic reptiles Two main body forms: plesiosauromorphs have long neck and small head, pilosauromorphs have short neck + large head Testudines: turtles, tortoises, terrapins Shell composed of a carapace and plastron May be covered in skin scutes/scales made of keratin Pseudosuchia: all living crocodilians and all archosauria more closely related to them than birds Crocodillia: 1-7 metres long Elongated snouts and flattened tails 2 gaits- low walk with sprawling limbs + high walk for speed Pterosauromoropha: extinct now, earliest vertebrates that developed wing flight Elongated 4th finger and membrane of skin Covered in hair like filaments called pycnofibres Dinosauria: 10,000 living species Elevated metabolisms and adaptations for social interactions

Answer 66

A mammal is a synapsid amniote with a dentary squamosal jaw articulation, middle ear with a chain of 3 bones, tooth replacement occurs once, prismatic enamel on teeth, occlusion between upper and lower molars (they fit together), two occipital condyles at the base of the skull, sweat glands including those specialised to produce milk, hair and fur. Class Mammalia contains all the living descendants of synapsida Body plan: Seven cervical vertebrae Three layers of skin- epidermis, dermis, hypodermis Vocal folds in larynx which allow sounds other than hissing Fur for insulation, protection, sensory, water proofing, camouflage Milk Respiration: Lungs are spongy Diaphragm divides thorax and abdomen Circulation: Four chambered heart Complete seepration between oxygenated and deoxygenated blood Digestion: Adaptations to herbivores diet- fermenting stomach (artiodactyls), coprophagy (rodents + lagomorphs) Excretion: Bilirubin (waste from blood cells)- brown faeces Excrete urea Kidneys have distinguishable xotex and medulla Nervous system: Neocortex- unique to mammals, grey matter, deals with cognition + spatial reasoning + communication Ear made of three bones Well developed ear with colour vision Sense of smell is primary sense in most mammals Reproduction: Ancestral condition: produce undeveloped young- soft shelled eggs (monotremes), direct vivipary (marsupials) Placental mammals: prolonged inter uterine development Mammary glands producing milk- prolacteal fluid may have evolved to keep eggs moist and free from infection. Monotremes have a mammary patch, marsupials and placentals teats The extinct groups that were before the mammals: -Pelycosauria: paraphyletic taxon of basal synapsids Lack of epidermal scales have osteoderms and scutes instead -therapsida: taxon of advanced synapsids Mostly erect gait Large temporal fenestra which increases bite force Differentiated teeth- incisors, canines, molars Endotherms Cynodonts is the group that gave rise to mammals Split into australosphendia ( which contains the monotrematas) and the theriiformes (marsupialia + placentalia) -Monotremata: Platypus and echidna Single duct for urinary, digestive, and reproductive systems Eggs hatch within 10 days Modern species lack teeth as adults Electro reception Venom- male monotremes have spur on leg, powerful venom in platypuses -Marsupialia: Pouch Male has no baculum, forked penis, srcotum often anterior to penis Female two lateral vaginas each leading to a uterus, a third median vagina for giving birth Epipubic bones Marsupium- external development of infant -Placentalia: Eutherian placental animals Specifically a chorioallantoic placenta (chorion + allantois) Marsupials also have a choriovitelline placenta (chorion + yolk sack) Loss of epipubic bone which prevented expansion of torso needed for prolonged pregnancy. It developed into a baculum

Bilateria Flashcards

(90 cards)