Transcript 31.1 Animals are multicellular heterotrophs without cell

Overview of Animal
Diversity
• Animals are multicellular
heterotrophs that are diverse in
form and habitat, are mobile,
reproduce sexually, and have
characteristic embryonic
development. (p. 618)
Animals
• Taxonomists have traditionally
created phylogenies by
comparing anatomical features
and embryological development.
(p. 620)
Parazoa lack a definite symmetry
and organized tissues.
Eumetazoa have a definite
symmetry and organized tissues.
(p. 620)
Bilateria -having bilateral
symmetry. (p. 620)
• Bilateral animals further split
into groups with and without a
body cavity (coelom). (p. 620)
This is a distinction long used for
classification
Types of Body Cavities
pg 625
• Acoelomate -no body cavity
– flatworms
• Pseudocoelomate-pseudocoel located
between mesoderm and endoderm
– roundworms, rotifers
• Coelomate- body cavity completely
contained within mesoderm
– many members inc Homo sapiens
Protostome/ Deuterostome
• Protostome– Spiral Cleavage
– Determinate Devo
– Blastopore (invagination of blatula) becomes
mouth
• Deuterostome
– Radial Cleavage
– Indeterminate Devo (stem cells)
– Blastopore becomes anus
Segmentation
• Each segment may have full set of organs
– Life may continue if a segment is injured
– Facilitates more complex locomotion
• 32.3 Acoelomates are solid worms that
lack a body cavity.
– Flatworms (platyhelminthes), simple body
structure with ability to regenerate lost parts(page 642)
• 32.4 Pseudocoelomates have a simple
body cavity.
The Pseudocoelomates
• In the pseudocoelomates, circulation
occurs in a pseudocoel, not in a defined
circulatory system. (p. 646)
– Nematodes-ex: parasitic Trichenella (raw pork)
(page 647)
• Puzzles related to Animal Evolution
• "Evo-Devo" and the Roots of the Animal
Family Tree
• Origin of sponges?
– The multinucleate hypothesis, the colonial
flagellate hypothesis, and the polyphyletic
origin hypothesis all try to account for the
origin of metazoans from single-celled protists.
(p. 630)
• Puzzles related to Animal Evolution
• A large diversity of animal body plans
occurred around the Cambrian period, with
no new innovations since. (p. 630)
Cause?...
– the emergence of predatory lifestyles or
geological factors.
– debut of Hox genes within developing animal
embryos. (p. 630)
INVERTEBRATES
• 33.1 Mollusks were among the first
coelomates.
Mollusk Body Plan
• The evolution of a coelom was a
significant advance in animal body structure
because it repositions fluid and allows
complex tissues and organs to develop.
(p. 652)
• The molluscan body plan is bilaterally
symmetrical, with an efficient excretory
system and a muscular foot for locomotion.
(p. 653-4) Many have rasping (scraping)
tongue called radula.
• Major Classes of Mollusks
• Major classes of mollusks include the
class Gastropoda (snails and slugs), class
Bivalvia (bivalves), and class Cephalopoda
(octopuses, squids, and nautiluses). (pp.
656-657)
33.2 Annelids were the first segmented animals.
Segmented Bodies
• • Segmentation was a key transition in
animal body plans, because similar
segments can be individually controlled for
different functions. (p. 658)
• Three principal features of annelids are
repeated segments, specialized segments,
and connections between segments. (p. 658)
• Tube within a tube body plan. (p. 658)
• Locomotion --hydrostatic skeleton forces
fluid from one segment to the next. (p. 658)
Major Classes of Annelids
• 12,000 species , three classes:
– Polychaeta (polychaetes), Oligochaeta
(earthworms), and Hirudinea (leeches). (pp.
660-661)
33.3 Lophophorates appear to be a transitional
group.
Lophophorates
• The marine phyla Phoronida (phoronids),
Ectoprocta (bryozoans), and Brachiopoda
(brachiopods) are characterized by a ridge
around the mouth bearing ciliated, hollow
tentacles (lophophore) that functions in gas
exchange and food collection. (pp. 662-663)
33.4 Arthropods are the most diverse of all
animal groups.
Arthropod Body Plan
• Over two-thirds of all named species on the earth
are arthropods. (p. 664)
…arthropod body plan
• Jointed appendages -– legs, antennae, and mouthparts, and an
exoskeleton of chitin and protein used for
protection and water loss prevention,
– most diverse phylum on the planet. (p. 664)
– Arthropods are segmented, with some
segments fused into functional groups (ex:
head, thorax) (pp. 665-666)
…arthropods
• The exoskeleton is secreted by, and fused
with, the epidermis, and provides a hard
surface for muscle attachment. (p. 666)
• All arthropods have an open circulatory
system; some have adaptations such as
compound eyes, a respiratory system
composed of tracheae, and an excretory
system composed of Malpighian tubules.
(pp. 666-667)
• Why must arthropods molt?
A Major Group of Arthropods:
Crustaceans
• Most crustaceans (35,000 species) have two
pairs of antennae, three types of chewing
appendages, and various pairs of legs. (p.
668)
• Crustaceans are found in marine,
freshwater, and terrestrial habitats. (pp. 668669)
Major Classes of Arthropods:
Arachnids
• Arachnids (57,000 species) have a pair of
chelicerae, a pair of pedipalps, and four
pairs of walking legs. (p. 670)
– Two major orders are Araneae (spiders) and
Acari (mites and ticks). (p. 670)
Major Classes of Arthropods:
Centipedes and Millipedes
• Centipedes (class Chilopoda) and
millipedes (class Diplopoda) are made of a
head region followed by numerous similar
segments.
– Centipedes have one pair of legs per segment,
and millipedes have two pairs per segment.
– (p. 671)
Major Classes of Arthropods:
Insects
• Class Insecta is the largest group of organisms
on the planet, living in nearly every possible
habitat. (p. 672)
• Most are relatively small, and contain three
body sections: head, thorax, and abdomen,
with three pairs of legs attached to the thorax,
and one pair of antennae. (p. 674)
• Most insects have compound eyes. (p. 674)
…insects
• Sensory hairs, tympanal organs (sense
vibrations such as sound waves) and
chemoreceptors all act as sense receptors in
insects. (p. 675)
• Many insects undergo either simple or
complex metamorphosis. (p. 675)
• What are the stages of complete
metamorphosis?
Echinoderms
• 33.5 Echinoderms are radially
symmetrical as adults.
Deuterostome Development and an
Endoskeleton
• Echinoderms are marine animals with hard
calcium plates forming a true endoskeleton
in young individuals. (p. 676)
Echinoderm Body Plan
• All echinoderms are bilaterally symmetrical
during larval development, and become
radially symmetrical as adults. (p. 678)
• Echinoderms have a five-part body plan
with a central, branched nerve ring and an
endoskeleton composed of calcium-rich
plates (ossicles). (p. 678)
• Many echinoderms can regenerate lost
parts, but in most of them, reproduction is
sexual and external. (p. 679)
• Echinoderms have a water
vascular system
– Water pressure fills tube feet which allows
movement and feeding. They have enough
strength to pull apart a clam shell, which I
cannot do. Then they stick their stomach inside
and start digesting.
• Major Classes of Echinoderms
• There are six living classes of
Echinoderms: Crinoidea (sea lilies and
feather stars), Asteroidea (sea stars or
starfish), Ophiuroidea (brittle stars),
Echinoidea (sea urchins and sand dollars),
Holothuroidea (sea cucumbers), and
Concentricycloidea (sea daisies). (p. 680)
VERTEBRATES
• 34.1 Attaching muscles to an internal
framework greatly improves movement.
The Chordates
• Four features characterize the chordates:
(1) single, hollow nerve cord; (2) a flexible
notochord present at some developmental
stage; (3) pharyngeal pouches connecting
the pharynx and the esophagus (gill slits in human
embryos); (4) a postanal tail at least during
embryonic development. (p. 684)
• 34.2 Nonvertebrate chordates have a
notochord but no backbone.
The Nonvertebrate Chordates
• Tunicates possess a notochord and a nerve
cord as larvae, but look at them as adults!
(p. 686)
• Lancelets are fishlike marine chordates
with a permanent notochord running the
entire length of the dorsal nerve cord. (p.
687)
• 34.3 The evolution of vertebrates
involved invasions of sea, land, and air.
Characteristics of Vertebrates
• Vertebrates -vertebral column instead of a
notochord and a distinct head. (p. 688)
• The history of the vertebrates -they
invaded the sea and then the land. (p. 689)
Vertebrates are distinguished
from other chordates
• Neural crest (page 688 and 1090-91)
• Internal organs
• Endoskeleton of bone or cartilage for size
and movement
• Fishes
• Fish were the first vertebrates and are the
most diverse and successful vertebrate
group. (p. 690)
• Key characteristics of fish include a
vertebral column, jaws and paired
appendages, gills, single-loop circulation,
and nutritional deficiencies (which means
they need to eat nitrogen). (p. 690)
• Sharks eventually became dominant sea
predators, partially due to a skeleton
composed of calcified cartilage. Sharks
were also among the first vertebrates to
develop teeth. (p. 695)
• What do you know about shark’s teeth?
• Bony fish -- ossification provided a strong
base for muscle attachment and evolved in
fresh water. (p. 696)
– swim bladder for buoyancy,
– a lateral line sensory system,
– and a gill cover (operculum) to permit water to
be pumped over the gills. (pp. 696-697)
• Amphibians
• legs
• cutaneous respiration
• lungs, pulmonary veins
• partially divided heart. (p. 698)
• evolved from lobe-finned fishes.
• Include frogs and toads, salamanders, and
caecilians. (pp. 699-701)
•
Reptiles
• Key characteristics of reptiles include the
amniotic egg, dry skin, and thoracic
breathing (expand ribcage). (p. 702)
• Turtles, lizards and snakes, tuataras, and
crocodiles. (pp. 707-709)
•
Birds
• Modern birds retain many reptilian
characteristics, but lack teeth and have
vestigial tails. They are distinguished from
living reptiles by feathers and the presence
of a thin, hollow flight skeleton. (p. 710)
• Descended from dinosaurs
• Mammals
• Hair, mammary glands, a placenta,
heterodont dentition, the ability to digest
plant material, keratinized hooves and
horns, and flight capability (in bats). (pp.
714-716)
• The Orders of Mammals
• Mammals were not common until
dinosaurs disappeared. Modern mammals
fall into one of three categories:
monotremes, egg-laying mammals;
marsupials, pouched mammals; and
placentals. (pp. 717-718)
• 34.4 Evolution among the primates has
focused on brain size and locomotion.
Primates
• Grasping fingers and toes and binocular
vision are two features that allowed
primates to flourish. (p. 720)
• Modern prosimians include lemurs,
lorises, and tarsiers, while anthropoids
include monkeys, apes, and humans. (pp.
720-721)
-Zaboomafoo from PBS
• Australopithecines
• Bipedalism marked the beginning of
hominid evolution, although the reason for
such evolution remains controversial. (p.
722)
• What are some possible reasons?
• Maybe it’s just so we can hold hands.
• The Genus Homo
• The first humans (Homo habilis) evolved
from australopithecine ancestors about 2
MYA. (p. 724)
• Homo erectus replaced H. habilis, and is
believed to have come out of Africa. (pp.
724-725)
• Homo sapiens is both the only surviving
species of the genus Homo and the only
surviving hominid. (p. 726)
• Humans are the only animals that can
effectively make tools, that have refined and
extended the ability to use conceptual
thought, and that can use symbolic language
and shape concepts and experiences with
words. (p. 726)
…but, Think Tank in National Zoo...
Taung Skull
2.5 myo
Australopithicus afarensis
Taung Skull Site
Human Evolved from Monkey?
• If humans did evolve from monkeys (or
gorillas) or anything from this chart, how
would this change the phylogenic tree?