Lecture 15 Flashcards
What is the def of animals
- multicellular eukaryotes and chemoheterotroph that ingests and digests food (a monophyletic group)
What are chemoheterotrophs?
- obtain both energy and carbon by consuming organic materials (similar to fungi, except animals also ingest food
What are the simplest living animals?
sponges! no true tissues
What are Ediacaran?
- sponges are earliest known animal fossils
- choanoflagellates
What are Opabinia
- extinct clade and controversial : some thought Arthropod? ; prob an extinct phylum
- five strange, mushroom-shaped eyes
- weird proboscis
- no jointed appendages
describe arthropods
- bilaterally symmetrical
- segmented
- with hardened exoskeletons
- with JOINTED APPENDAGES (legs, antennae)
What are non-bilaterian animals?
radial or no symmetry (earliest fossils)
ex. sponges, corals, anemones, jellyfishes
describe sponges
- multicellular but lacks true tissue
- no symmetry
- no muscles and nerves
- all are benthic (lower level)
how do sponges feed?
- most are suspension feeders
- feeding cells capture food particles from water currents moving through cavities in the body
- many harbour photosynthetic symbionts
How do sponges move?
- most adults are sessile
- limited shape changes occur in some species due to coordinated changes in cells
- dispersal is typically by ciliated larvae
What does sessile mean?
- fixed in one place; immobile
how do sponges reproduce?
- asexually
- if sexual, fertilization is often internal
Where do sponges usually live?
- mostly marine but also fresh waters (~8500 species)
REVIEW sponges in fresh water
if you pull up and rock or a stick in fresh water, there is sponge on it with symbiotic algae so it is green. this allows photosynthetic symbionts
What sponge reef was rediscovered 25 years ago after it was thought to be extinct about 40 million years ago?
- glass sponge reefs off the coast of BC
- 3 species forming deep reef clutsters
- very fragile and weighs nothing
to who are the reefs habitats to?
- important fish and shrimp habitats
What type of phylum are sponges?
- Porifera
- has pores and holes
what do sponges incorporate
- choanoflagellates which are feeding cells that circulate water with flagella
What are choanoflagellates
- free-living protists
- ancestral to one of the cell types that inhabit sponges (the choanocytes)
- other cells are amoeboid and mobile
What kind of feeders are sponges and what do they tolerate?
- suspension (filter) feeders on bacteria and organic detritus in water
- tolerant of low oxygen levels, consistent with a late Precambrian origin
Whats the embryology of sponges?
- a fundamental division in animals is early development, which is diploblastic (2 tissues) in non-bilaterians other than sponges, involving only an external extoderm layer and an internal endoderm layer
give an example of a synapomorphy with the Phylum Cnidaria
- species of anenomes, corals, jellyfish, sea-fans, and hydroids
- which all produce special stinging cells (cnidocytes)
What are bilaterians
- have a bilateral symmetry
- are triploblastic
- divided into 2 main groups, the Protostomes and the Deuterostomes
What is triploblastic?
- 3 layers: Ectoderm, mesoderm, and endoderm
explain the protostomes
- subgroup of bilaterians
- includes most worms, molluscs, and the ANTHROPODS (insects, spiders, crustaceans)
- development of head end of the embryo before the posterior
explain the deuterostomes
- composed of the echinoderms and the Chordata (with a notochord supporting the back at some stage)
- embryo develops posterior end first, then head
describe the evolution of bilaterally symmetrical animals
- development of central nervous system and cephalization
explain cephalization
- formation of an anterior head region with concentrated nerve cells
- nerves are concentrated at the head end
Where are sensory appendages concentrated with bilaterally symmetrical animals
- sight, hearing, taste and smell tend to become concentrated in the head region (eyes, antennae, sensory hairs, etc.)
for animal diversity, what is the relative diversity of animal lineages (whats the majority)
- most animal species are protostomes
- about 70% of all known species of animals on Earth are insects, most of them BEETLES
how do suspension feeders feed
- capture food by filtering out particles floating in water or air
- aquatic animals
- barnacles use specialized legs to capture plankton
How do deposit feeders feed
- ingest organic material that has been depostied within a substrate or on its surface
- earthworms on land
- sea cucumbers use feeding tentacles to mop up detritus from the seafloor
how do fluid feeders feed
- suck or mop up liquids like nectar, plant sap, blood, or fruit juice
- butterflies and moths drink nectar through their extensible, hollow proboscis
How do mass feeders feed?
- take chunks of food into their mouths or whole prey organisms
- lions bite off chunks of meat from prey carcasses
explain what each 4 ecological roles feed on
- detritivores feed on dead organic matter
- herbivores feed on plants or algae
- carnivores feed on animals
- omnivores feed on a combination of plants, animals, fungi, protists, archaea and/or bacteria
What are the 5 different types of limbs
- lobe-like limbs (velvet worms uses to crawl)
- jointed limbs (crabs, anthropods, vertebrates)
- parapodia (polychaete worms use bristled parapodia to crawl and swim)
- tube feet (echinoderms like a sea star uses tube feet to crawl
- tentacles (octopuses uses them to crawl and grab prey)
LImbs usually for locomotion and feeding
What confirms the close relationship between the deuterostomes?
- genomics
- 4 phyla of deuterostomes: Chordata, Cenoturbellida, Hemichordata, Echinodermata
- vertebrates are in the phylum Chordata
What are the 4 features that all 3 lineages of Chordates share?
- pharyngeal slits or pouches
- dorsal hollow nerve cord
- notochord
- muscular, post anal tail
where is the only notochord remnant in adult humans
- the intervertebral disks in the backbone
What is the Metaspringgina fossils at Marble Canyon BC cambrian
- Metaspriggina walcotti
- defintive vertebrate (fish-like) features: notochord, paired eyes, gill bars, swimming fishlike muscles, JAWLESS fish!
Whats another way to say tetrapods
- chordates with 4 limbs
What are the 3 tetrapod lineages
- amphibians
AMNIOTES:
- mammals
- reptiles and birds
What are amphibians?
- first land tetrapods
- most feed on land, but return to water to reproduce
- external fertilization
describe Anura (frogs and toads)
- stout-bodied
- lacks tail as adults
- large eyes
- adults are carnivores
- 4 limbs
- external fertilization in water (secual)
describe Urodela (Salamanders)
- slender-bodied
- has tails
- short 4 limbs
- large eyes
- most adults are carnivores
- sexual reproduction by internal fertilization in water
describe Gymnophiona (Caecilians)
- slender-bodied
- no limbs!!
- small skin-covered eyes that detect light
- prey on earthworms and other soil-dwelling animals, invertebrates and small fishes
- sexual reproduction internally
Review first amniotes
- all non-amphibian tetrapods are amniotes
- animals where females produce an amniotic egg
- reptiles and mammals forms a sister group: the synapomorphy of amniotic eggs was inherited from a common ancestor
- 4 membrane-bound sacs (amnion, chorion, idk the rest) enclosed in a shell that provide WATER, NUTRIENTS, GAS EXCHANGE, WASTE SEPARATION AND SUPPORT
- provides protection for survial on land!
WHat are the 4 living reptile lineages
Lepidosauria (lizards, snakes)
Testudinia (turtles)
Crocodilia (crocodiles, alligators)
Aves (birds)
- all carnivores except some turtles and some birds
describe some traits of reptiles
- amniotic egg
- thick skin with waterproof scales made of KERATIN to minimize water loss
- well-developed lungs
- birds and some extinct dinos has feathers also made of keratin
What are some of the key synapomorphies in mammals?
- hair and lactations (milk production from mammary glands)
- endothermy (trait linked to high activity and tolerance of cool climates)
compare the amniotic egg to a placenta
- yolk sac is reduced
- fluid-filled amniotic sac supports the embryo
- chorion membrane and the unique placental tissues of marsupials and placental mammals surrounds the sac
- gas exchange and waste removal is done via the placenta
What are the advantages of viviparity (live births)?
- protection inside female
- constant temp for development
- embryo is portable
review key messages
- vertebrate evolution: highly variable, non-linear, gave rise to many synapomorphies that define lineages
- loss of adaptations: snake and caecilian amphibians have lost legs, also whales and others; teeth in birds
