Lecture Exam PT 2 ( Animals 3-5)

what are the benefits of a chitinized cuticle?

- protects organs
-prevents water loss
-supports organs effects, locomotion
- specialized appendages ( spears, wings, hairs)

what are the drawback of having a chitinized cuticle?

-cannot grow so must shed periodically
- motling energetically expensive
-newly molted animals are unprotected until new exoskeleton hardens
-evolutionary constraints on size

what animals are apart of the basal ecdyszoans?

- priapulids( penis worms)
- kinorhynchs ( mud dragons)
- loriciferans

Priapulids: (penis worms)

three-part bodies (proboscis,
trunk, and tail); live in mud and
feed on slow-moving
invertebrates; major predators in
Cambrian

Kinorhynchs: (mud dragons)

live in marine sands and muds
and are virtually microscopic (1
millimeter or less). Bodies are
divided into 13 segments, each
with a separate cuticular plate.

Loriciferans:

are also less than
1 millimeter long. Body is divided
into a head, neck, thorax, and
abdomen and is covered by six
plates; miniaturized versions of
animals found in Cambrian

Nematoda

worm like- thread like
- phylogenetic position disrupted
-unsegmented
-pseudocoelomate
-dioecious and parthenogenetic
-many plant, animal, and human pathogens

Ascaris - round worm

-intestinal parasitic disease caused by Ascaris Lumbricoides
-eggs in human feces or untreated water can be picked up through contaminated food

Trichinosis

infectious, generally caused by eating undercooked pork
- various species of Trichinella, mainly T. spiralis

Enterobius Vermicularis

-pin worm
-causal agent of most common human parasitic disease developed in countries
- fecal- oral transmissiond

dracunculiasis ( guinea worm disease)

caused by nematode Dracunculus medinensis

Onychophora and tardigrades

- related to arthropods ( unjointed legs)
-like arthropods, but lost coelom body cavity, instead have hemocoel ( blood chamber)
-internal body cavity in which fluids bathe internal organs

Onychophora " velvet worms"

- segmented by lack jointed appendages
-cuticles with chitin
-Tropical/temperate
-squirt slime to subdue prey
-live in social groups
-elaborate behaviors

Tardigrada "water beards"

Microscopic
• Found worldwide
• 4-layered cuticle
• Extremely hardy
• Cryptobiosis resting state (like suspended
animation)
– Near freezing to
extreme heat (- 190°C to 70°C)
– High salinity
– Lack of Oxygen
– Have survived space
vacuum and radiation

what are arthropods characteristics

1. Jointed legs
2. Versatile and protective exoskeleton
3. Segmentation yields efficient locomotion
and neofunctionalization
4. Efficient tracheal gas exchange system
(Hexapoda, Myriapoda) or book lungs
(Chelicerates); oldest land animals (437
mya), about the same time as the earliest
vascular plants The jumping spider family: +5000 species
Arthropods
5. Highly developed sensory organs
6. Complex behaviors
7. Monophyletic and ancient (Cambrian)
8. Largest group of animals (nematodes may eventually be found to be as
numerous); 80% of all described animals
9. Thick exoskeleton reinforced with chitin or calcium carbonate
10. Successful in terrestrial habitats, along with amniote vertebrates

what are the different arthropod groups

-Trilobitomorpha
-Chelicerata
-Myriapods
-Crustaceans
-Hexapods

what does the General phylogeny of arthropods show?

-monophyly of arthropods undisputed
-"crown group" includes all recognized groups
most genes show :
- chelicerates as first diverging branch
- then myriapods
-then various groups of crustaceans (paraphyletic)w
hexapods

what is the body plan of an arthropod?

- skeletal muscle moves exoskeleton
- continuous, thick waxy, cuticle
- lost condition of coelom
- hemocoel
-fluid (hemolymph)

what is tagmosis

fusion of segments into functionalwh units (tagmata)

for hexapods and myriapods what is the tracheal system composed of?

composed of chitin-ringed tubes ( trachea) that connects directly to the air through openings in the body wall ( spiracles)

when were spiracles of myriapod fossils found?

428 mya

what are ommatidia?

eyes composed of units called

Trilobitomorpha

Trilobites = “Three-lobed”
• Three-lobed body plan
(Head/Thorax/Tail)
• Calcified exoskeleton
• Cambrian explosion (535-525 mya)
• Fully extinct after Permian mass
extinction (~ 250 mya)
• Very successful for over 250 my

subphylum Cephalothorax

-abdomen
• No antennae
• Six pairs of
appendages:
– Chelicerae
• Clawlike feeding
appendages
– Pedipalps
– 4 pairs walking legs

what are chelicerates characterized by?

y a head bearing two pairs of appendages modified to form
mouthparts, chelicerae and pedipalps (piercing instead of chewing; no
mandibles).
- no antennae
-Many chelicerates have four pairs of walking legs

what groups are also apart of chelicerates?

-pycnogonids (sea spiders)
- horseshoe crab
-arachnids

what is the oldest land animal from the fossil record?

scorpion
silurianw 437 mya

what is the chelicerata- arachnid anatomy?

-all spiders produce silk proteins in silk glands and spinnerets to produce silk thread
-earliest spiders use silk threads to protects eggs, line nests and wrap prey
-later elaborated to form web

Subphylum Myriapoda

" many legs"
-9 or more pairs
-antennae
- terrrestrial
tracheal system for gas exchange
2 classes wht

what are two classes of myriapoda?

diplopodaD and chilopoda

Diplopoda " double footed"

2 pairs of walking legs per segment
(fusion of 2)
• 25-100 body segments
• Feed on decaying plant matter
• Slow-moving
• Small jaws and legsV

Chilopoda

Terrestrial carnivores
• Fast-moving
• 1 pair of walking legs per segment
• Venomous claws

Crustacea

Highly specialized
appendages
• Only arthropods with 2
pairs of antennae
• Calcium carbonate with
chitin in exoskeleton
• 2 to 3 body segments
• 3 or more pairs of legs
• Abdominal appendages
(unlike insects that
have only thoracic
appendages)
• Mostly marine

what is the largest group of arthropods?

hexapods w

what was the first aniaml group to fly?

arthropods 300 mya ago

Arthropods

-Largest group of arthropods
-Insecta and Entognatha
-More than a million species
described, mostly insects
-Most are terrestrial
-Six legs; usually three tagmata (head,
thorax, abdomen)
-Insects the only invertebrate group
(and the first animal group) to have
evolved powered flight

what is the most basal lineage of hexapoda?

Entognatha E

Entognatha

- internal mouthparts
- no wings
- springtails, bristletails, and maybe proturans

Protura

• Small soil-dwelling hexapods
• No eyes, wings or antennae
• “Coneheads”
• Basal hexapods; probably a separate group
sister to the rest of the hexapods (Entognatha +
Insects)

Collembola

Springtails
• Very diverse soil-dwelling animals
• Except for one family, lack tracheal system
• Possess a specialized abdominal, tail-like
appendage folded under the body; when
alarmed this can flick the animal meters away

Diplura

One of several groups called “bristletails” (some
“bristletails” are actually insects)
• Paired cerci on posterior (“bristle tail”)
• No eyes, long antennae, bead-like segments
• Biting mouthparts, predaceous

what are the general characteristics of insects?

- single pair of antennae
- wing extensions of the cuticle
- 3 pairs of legs attached to the thorax
-tracheal system for gas exchange
-well developed senses
- internal fertilization
3 tagmata : head, thorax, and abdomen

Have insects always had wings?

no, some of the earliest insects were wingless, most have two pairs of wings; some have lost wings secondarily

what are the two insect life cycles

-Hemimetabolous (incomplete)
- Holometabolous (complete)

Insect flight

- only invertebrates to develop powdered flight
-oldest fossils of flying insects ( carboniferous 300 mya)
- major contributor to insect success
- enabled dispersal across land
- wings only evolved once

what are the theories of how insects wings initially evolved?

gills, gliding, heat fans, and swimming

what is the direct flight mechanism?

wing muscles directly at wing base

what is the indirect flight mechanism?

wing muscles attach to the thorax and deform it, causing the wings to moveH

Hemiptera ( sucking mouthparts)

-half wings
-hemimetabolous
-aphids, leafhoppers, cicadas
- some are blood sucking

Orthoptera ( enlarged hind legs)

- straight wings
-hemimetabolous
- some produce sound by rubbing wings against each other or legs
ex: grasshoppers/crickets

Coleoptera (hardened forewings)

shield wings”
• Beetles
• 400,000 spp.
• Most species of any animal
group
• Elytra (shield-like
forewings) open new niches
(burrowing, etc.)
• Holometabolous

Hymenoptera (thing transparent wings)

membrane wings”
• 125,000 spp.
• holometabolous
• Eusocial behavior
• Ants, wasps, bees
• Haplodiploid
• Some venomous

Lepidoptera ( scaled wings)

scale wings”
– 250,000 spp.
– Butterflies and moths
– holometabolous

Diptera ( hind leg modified into halteres)

– “two wings”
– 120,000 spp.
– Halteres control
balance, guidance and
stability during flight
(gyroscopes)
– Flies, mosquitos
– holometabolous

Deuterostomes

blastopore forms anus, cleavage radial and intermediate and coelom formation enterocoelous ( all coelomates)

what are the characters of deuterostomes?

- triploblastic coelomate
-radia cleavage
- formation of mouth at opposite end of the embryo
- development of coelom from mesodermal pouches that bud from archenteron walls
- internal skeletal system and segmentation

what is the ancestral conditions for bilateria?

Blastopore becomes the anus
• Radial cleavage
• Suggests protostomes are derived

what are the ancestral conditions for the deuterostomes?

Bilateral symmetry
• Segmentation
• Pharyngeal slits
• Chordates retain these characters
• Suggests that echinoderms are derived

what ae the two clades that have duterostomes?

Ambulacrarians (Echinoderms and Hemichordates)
• Chordates

Hemichordata

• Used to be considered a chordate
subphylum
• Retain bilateral symmetry of larvae as
adults
• Acorn worms and pterobranchs
• Acorn worms are solitary marine
worm-like animals that live in burrows;
deposit feeders or suspension feeders
• Most similar to the common ancestor
of chordates and the rest of the
deuterostomes

what are the different clades that fall under echinoderm?

- asteroidea - sea stars
-ophiuroidea - brittle stars
- echinoidea - sea urchins
-crinoidea - sea lilies
- holothuroidea - sea cucumbers

what are the characteristics of echinoderms?

- all marine, no osmoregulation
- sessile or slow moving, lost pharyngeal slits
- adults radially symmetrical
- larvae bilaterally symmetrical
- most species gonochoric and some hermaphroditic
- some capable of regeneration lost parts
- thin skin covering the endoskeleton
- water vascular system and tube feet in all groups

what are the clades of chordata?

urochordata and cephalochordata

Pikaia

- chordate from the cambrian period
- described as a polychaete worm
-segmented with a notochord ( chordates are segmented)

what are the chordate characters?

1. notochord
2. muscular, postanal tail
3. pharyngeal slits
4. dorsal nerve cord
5. endostyle

what are the characters of vertebrates?

Anterior skull containing a relatively large
brain
- Rigid endoskeleton (bony or cartilaginous)
supported on vertebral column (except
hagfishes, which some exclude from the
vertebrates)
- Well-developed closed circulatory system
driven by contractions of a ventral heart
- Coelom with suspended organs

what is the oldest vertebrate?

haikouichthys ( 530 mya)
- distinct head, tail and gills

conodonts

- tooth like structures common in cambrian strata up to the jurassic
- distinctive index fossils
- now part of jawless vertebrates
- made up of hydroxyapatite

cyclostomes- hagfishes

- cartilaginous endoskeleton
-not supported by complete vertebral column;
- persistent notochord ( not technically vertebrates)
- sister to lampreys - structural differences
-Skull not complete; brain with no cerebrum or cerebellum
-No jointed vertebral column; cartilaginous
-Tooth-like structures of keratin
-All are marine
-Scavengers, predators and suspension feeders
-Direct development (no larval stage)
-Notable ability to produce defensive slime

Cyclostomes- lampreys

Adult is sometimes a fish ectoparasite and
larvae are filter feeders (some adults do not
feed)
-Complete metamorphosis to adult
-Complete braincase; rudimentary vertebral
column
-Cartilaginous endoskeleton; horny keratinous
teeth
-Molecular data indicate hagfish and
lampreys are sisters and that the two together
are sister to other vertebrates

jawed fishes

- first observed in late ordovician fishes
- presumed to have developed from the first gill arch
- probably adaptive to originally in buccal pumping of water across the gills
- jawed cartilaginous and bony lineages represented
- radiated in the devonian and replaced most of the jawless fishes

Placoderms - Jawed fishes

- teeth seen as the outgrowths of the jaw

Chondrichthyans ( sharks, rays, and chimaeras)

• Mostly marine
• No lungs or swim bladders
• Cartilaginous skeleton
• Internal fertilization
• Many produce live young,
but do not exhibit parental
care
• Skin covered by placoid
scales,
- homologous to
vertebrate teeth with a
central pulp surrounded
by dentiner

rays

Close relatives of sharks
• Contain the largest number of
species
• Dorsiventrally flattened bodies,
enlarged pectoral fins fused to
the head and ventral gill slits
• Mostly marine and feed on
invertebrates close to the sea
floor in coastal areas; large
Manta rays are pelagic and filter
feed on plankton

what are the characters of bony fish?

Marine and freshwater
- Calcium phosphate in cartilage matrix to form bony
skeleton
- Fins with rods of cartilage for support in ray-finned
fishes; fleshy lobed fins in lobe-finned fishes
- Heart with two chambers (atrium and ventricle)
- Most have swim bladders derived from lungs (lungs
represent a primitive character found in the earliest
bony fishes and retained in the basal lineages of
ray-finned fishes, such as bichirs and reedfishes,
and also in lobe-finned fishes)

what two fishes are apart of the lobe-finned fishes (sarcopterygians)

coelacanths and lungfishes

Lungfish ( air breathers- devonian origin)

Six living species
representing the
remnants of a larger
Mesozoic distribution
• Retain many
characteristics of ancient
bony fishes and
Sarcopterygian fishes
• Lungs homologous to
those of tetrapods

what were the problems associated when moving to land?

1. mass and structural support
2. locomotion
3. air breathing
4. feeding ( no more filter feeding)
5. sensory
6. water loss
7. reproduction ( earliest animals fully aquatic and reproduced in water)

Tiktaalik

Fossil discovered in 2004 in northern Canada
• Dates from late Devonian (375 mya)
• Considered a sarcopterygian fish species
• Important as a transitional animal; limbs intermediate
between fully aquatic fishes and terrestrial tetrapods

what are the general characters of the amphibian clade?

1. skeleton mostly bony
2. four limbs ( quadrupedal)
3. three chambered heart
4. gas exchange through smooth moist glandular skin
5. carnivorous as adults
6. both lungs and gills during lifecycle

anura

• Frogs and toads
• Carnivorous and tailless as adults; herbivorous tailed larvae
• Glandular skin defensive
• Warty frogs called toads
• Larvae “tadpoles” with internal gills
• Complex vocalizations and breeding behaviors

caudata

Salamanders
• About 550 species; earliest date from
Jurassic
• Moist skins, skin glands
• Tailed as larvae and adults
• Capable of regenerating lost limbsa

apoda

• Caecilians
• Completely legless, nearly blind amphibians
• Mostly tropical, live in soils and are seldom seen
• Look like earthworms
• Earliest fossil caecilians date from Jurassic and had fully
developed legs and eyes
• Internal fertilization and development of young inside female
• Remarkable maternal care

what are amniotes?

- have covered eggs and internal fertilization
- (340 mya to present)
- shell and shell membranes protect and retards evaporation of water

what are the different parts of the extraembryonic membrane?

chorion- outermost outer membrane, used in gas exchange
allantois- encloses wastes and used in gas exchange
amnion- protects embryo
yolk sac- provides nutrients

what are the different amniote lineages?

- diapsids
- synapsids
- anapsides

what are diapsids?

have 2 fenestrae behind the orbital linings of the skull ( reptiles)

what are synapsids?

have a single
opening (“mammals”)

what are anapsids?

have no
opening, but this is a
derivation in a single
lineage (turtles) of diapsids

what are the extant diapsid reptlies?

- testudines
- lepidosauria
- archosauria

Testudines - Turtles

-Fossils date from Late Triassic (215-220 mya
-ca. 300 extant species; mostly aquatic
-Dorsal carapace and ventral plastron are
fused vertebrae, ribs and dermal bone.
-Lack teeth
-Have an anapsid skull; however, they are
derived diapsids based on molecular data
-sister to the Archosaurs
-All are oviparous (egg-layers)

Lepidosauria - tuatara - squamata ( lizards)

Scaled skin (squamata); scales of keratin
produced by the epidermis
- Extremely diverse incudes terrestrial,
burrowing, aquatic, arboreal and aerial
members
- Most have four limbs but in many the limbs
are reduced and are absent in the glass lizards
- Most have moveable eyelids
- Oviparous (egg-layers) and Viviparous (livebearers)

Lepidosauria - squamata ( snakes)

Derived lizards (Cretaceous)
- Limbless, always lacking pectoral girdle
(Hox genes), and usually also the pelvic
girdle (vestigial in some snakes, e.g.,
pythons and boids)
- Numerous vertebrae (body basically an
extended thorax)
- Highly kinetic skull
- No movable eyelids
- Modified salivary glands produce venom in
20% of species

archosaurs General characteristics

Crocodilians, pterosaurs, dinosaurs and
birds
• Date from the late Permian/early Triassic
• Synapomorphies:
• Teeth set in sockets
• Openings in front of the eyes and in
front of the jaw
• A ridge on the femur that permitted
muscle attachment allowing

Archosauria - Crocodilians

Mostly unchanged for 200 My
- ca. 23 extant species, widespread
(tropical aquatic) top predator.
- Elongate, well reinforced skull with
massive jaw muscles
- Teeth are set in sockets - same as
dinosaurs (a synapomorphy for all
archosaurs). Mammals evolved these
independently
- Oviparous
- Closest living relative to birds

Archosauria - birds

Ca. 10,000 species
• Forelimbs modified for flight but some do not fly
(Paleognaths and many island endemics)
• Feathers, no teeth (developmentally repressed)
• Four-chambered heart
• Uniquely efficient respiratory system
• Semi-solid uric acid waste
• Endothermic
• Light weight skeleton - hollowed bonesco

Confuciusornis

Early unequivocal bird discovered in
China
• Cretaceous (125-140 mya)
• Claws on wings
• First toothless bird with beak
• Feathers definitely enabled powered
flight (although other non-flying
dinosaurs also produced feathers)

how many times did powered flight evolve in animals?

3 times in vertebrates
1 time in invertebrates

Archosauria - Pterosaurs

• Pterosaurs were the first
vertebrates to evolve powered flight;
very diverse
•Triassic to Cretaceous (228-66 mya)
• Hollow bones, keeled breastbone,
air sacs/lungs similar to birds
• Extinct at the K/T boundary