Exam 2 Flashcards
Deuterostome development
Eight-cell stage is radial and indeterminate
Folds of archenterpn form coelom
Anus develops from blastopore
Sponge structure
(1) sponges are suspension feeders, capturing food particles suspended in the water that passes through their body
(2) water is drawn through pores into a cavity called the spongocoel and out through an opening called the osculum
(3) sponges consist of a gelatinous noncellular mesohyl layer between 2 cell layers
First step for categorizing animals
Diploblasty vs Triploblasty as developing:
Diploblastic: 2 germ layers:ectoderm (outside), endoderm (inside)
Triploblastic: 3 germ layers: Ectoderm - leads to skin and nervous system, Endoderm - leads to digestive system, Mesoderm (middle) - leads to everything else (circulatory, bone, muscle, etc)
2nd step for categorizing animals
Radial symmetry in adults or Bilateral symmetry:
Radial: 2 planes, usually only in diploblastic organisms, ctenophores, cnidarians
Bilateral symmetry: single plane, anterior side (brain + sensory organs), posterior side (digestive track), dorsal side (top), ventral side (bottom)
Body cavities
Coelomates: tube within a tube, enclosed body cavity completely lined with mesoderm
Acoelomates: no coelom “just a tube”
Pseudocoelomates: enclosed body cavity that is partly lined w/mesoderm
How many living species of animals have scientists identified?
1.8 million
Eukaryotes are
cells with nucleus
- lack cell walls
- heterotrophs: carbon comes from other organisms
- motility
- all except sponges have 2 systems: nerve cells, muscle cells
- basal group is phylum porifera (sponges)
synapomorphy of heterotrophs is
multicellularity
Animilia group includes
Porifera (sponges), Ctenophora (comb jellies), Cnidaria (jellyfish, coral, sea anemones), Acoela, Rotifera (rotifers), Platyhelminthes (flatworms), Annelida (segmented worms), Mollusca (snails, clams, squid), Nematoda (roundworms), Arthropoda (insects, spiders, crustaceans), Echinodermata (sea stars, sand dollars), chordata (vertebrates, tunicates)
Protostome group includes
Rotifera, Platyhelminthes, Annelida, Nematoda, Arthropoda
Deuterostome group includes
Echinodermata, Chordata
Deuterostome group includes
Echinodermata, Chordata
Choanoflagellates vs Sponges
Individual choanoflagellate is a single cell
Sponges have collar cells (choanocytes) - the tail makes a current to give oxygen to cell, but multicellular so many cell types
Animal body plans vary according to
organization of the animal’s tissues
Tissues are
collections of specialized cells isolated from other tissues by membranous layers
During development, three germ layers give rise to
the tissues and organs of the animal embryo
Radial symmetry occurs in mostly ______ organisms
sessile or planktonic
Sessile organisms
organisms anchored to the benthic environment (to the bottom of the ocean)
Bilateral symmetry allows organisms to
move actively
The Diploblastic organisms are
Ctenophores and Cnidarians
The triploblastic organisms are
Acoela, Rotifers, Platyhelminthes, Annelids, Mollusca, Nematodes, Arthropods, Echinoderms, Chordates
The zygote of an animal undergoes a series of mitotic cell divisions called
cleavage
An 8-cell embryo is formed by ____ rounds of cell division
3
Blastula
In most animals, cleavage produces a multicellular stage called a blastula. The blastula is typically a hollow ball of cells that surround a cavity called blastocoel (innermost empty space)
Gastrulation
Most animals also undergo gastrulation, a process in which one end of the embryo folds inward, expands, and eventually fills the blastocoel, producing layers of embryonic tissue: the ectoderm, and the endoderm
Archenteron
Innermost compartment: The pouch formed by gastrulation which opens up to the outside via the blastopore
Blastopore
important for protozome and deuterozo,e development
Endoderm
the endoderm of the archenteron develops into the tissue lining the animal’s digestive tract
Protostome development
(1) Cleavage: The eight cell stage is spiral and determinate: each cell has a purpose and cells dont sit atop each other
(2) Coelom Formation: solid masses of mesoderm split and form coelom
(3) Fate of the blastopore: Mouth develops from blastopore
Deuterostome development
(1) cleavage: eight cell stage is radial and indeterminate (each cell can lead to a new zygote)
(2) Coelom formation: folds of archenteron form coelom
(3) fate of the blastopore: anus develops from blastopore
The morphology-based tree divides bilaterians into 2 clades:
deuterostomes and protostomes
Recent molecular studies indicate three bilaterian clades:
deuterostomia, ecdysozoa, and lophotrochozoa
Key synapomorphy of ecdysozoans
they shed their exoskeletons through a process called ecdysis
Lophotrochozoans are defined by either
lophophore feeding structures in adult form or trochophore larva in developing form
3 major clades of deuterostomia
Hemichordata, chordata, echinodermata
Sponge traits
- known to be benthic
- usually suspension feeders (capture food particles suspended in the water that passes through their body)but can also be predators
- adults are sessile - larvae can swim in water column
- collected from ocean floor for cleaning: medical use: have toxins being explored as chemotherapy
- sedentary and live in marine or freshwater
- basal animals that lack true tissues
Choanocyte and amoebocyte cell types in sponges
(1) sponges lack true tissues and organs
(2) amoebocytes are found in the mesohyl and play a role in digestion and structure
(3) choanocytes, elagellated collar cells, generate a water current through the sponge and ingest suspended food
Protostome evolutionary development
See image
The 4 main lineages within the cnidaria
Anthozoa ( anemones, corals, sea pens), hydrozoa ( hydrozoans), cubozoa ( box jellies), scyphozoa ( jellyfish)
Ctenophore traits
8 combs, 90% water,transparent, ciliated, larvae are free swimming
Traits of cnidaria
Diploblastic (have mesoglia), radial symmetry, tissues (gastrovacular cavity for digestion, veins, muscles)
Cubozoa traits
Predators, harpoon is extremely toxic
What level of toxins do anthozoa have?
None to low-level
Cell type that all cnidarians have
Cnidocyte : specialized cell that helps with prey capture, found in tentacles of cnidarians, basically harpoons in miniature form
Variations in cnidarian body plan
2 variations: the sessile polyp and the motile medusa
- a polyp adheres to the substrate by the aboral end of its body
- a medusa has a bell-shaped body with its mouth on the underside
Cnidarian life cycles may include a polyp and medusa form
True, see image
Protostomes are a ____ group comprising ______ major lineages
Monophyletic, 2
The lophotrochozoa and ecdysozoa
Lophotrochozoa includes
Rotifera, platyhelminthes, annelida, mollusca
Ecdysozoa includes
Nematoda, tardigrada, onychophora, arthropoda
Animals that undergo protostome development either have lophophores as adults or have trochophore larvae
Lophophores function in suspension feeding. Trochophore larvae swim and may feed.
Phylum annelida
Annelids have bodies composed of a series of fused rings
**The phylum is divided into 2 groups: Polychaeta (polychaetes) and Oligochaeta (earthworms and their relatives, and leeches).
Polychaeta
Members of class polychaetes have paddle-like parapodia that work as gills and aid in locomotion They are usually marine
Oligochaeta
Eat through soil
- pass soil through themselves
- hermaphrodites
- can be cut up and redevelop
Leeches
(1) mainly freshwater
(2) used during surgery (highly traumatic ones)
- keeps blood running smoothly through veins and arteries
- secrete a chemical called hirudin to prevent blood from coagulating
Phylum Mollusca
Includes snails and slugs, oysters and clams, and octopuses and squids
(1) Visceral Mass: includes most of the internal organs of the organism
(2) Mantle: outgrowth of the body wall that serves as covering for the visceral mass
- when a mollusk has a shell, mantle secretes the shell
(3) muscular foot: helps them stick to surface/crawl
- always located at base of animal
- if bivalve, foot is used as digging appendage
- if cephalopod, foot turns into tentacles
Class Bivalvia
(2 shells)
- shell w 2 parts and both parts have general characterisitics
(1) made of calcium carbonate
(2) hinged and close
(3) serve to protect animals
Marine and include many species of clams (burrow), oysters, muscles (can sort of move while attatched), and scallops (have eyes, can move fairly freely, are “fun”)
Bivalve structure
Remember thr adductor muscles and gills that filter O2 and food particles
Class gastropoda (gastropods)
- only class of molluscs that has transitioned to land
- about 3/4 of all living species of molluscs are gastropods
- most distinctive charscteristic is torsion: causes the animals anus and mantle to end up above its head
- usually gastropods that have lost their shell have toxins
Class polyplacophora (chitons)
(1) Oval shaped marine animals encased in an armor of 8 dorsal plates (calcium carbonate)
(2) Herbivorous: eat algae off rocks
- modified eating appendage: radula, good for scraping algae off rocks
(3) Reproduce sexually because of external organs
Class Cephalopoda (cephalopods)
(1) carnivores with beak-like jaws surrounded by tentacles of their modified foot
(2) have well developed head area: most developed brain of all invertebrates
(3) squid, octopus, cuttlefish, chambered nautilus
- except for nautilus, have internal shell or no shell at all
Squid
(1) have a different cell type: chromatophore: helps with camoflauge
(2) sophisticated eyes and lenses
(3) have a beak
(4) escape with ink release
(5) giant squid can take down sharks and whales
Chambered Nautilus
“Living Fossil”
(1) Each chamber is individually sealed and contains an amount of gas.
- provides the animal with bouyancy
- can regulate its density by injecting or removing fluid into these chambers through a system of tubes
(2) the siphuncle and septa work together to move animal in water column
- the siphuncle pushes air into each septa to move up in water column
Ecdysozoa
(1) grow incrementally: molting
(2) exoskeleton provides structure and protection
(3) are the most species-rich animal group
(4) are covered by a tough coat called a cuticle
- the cuticle is shed or molted through ecdysis
(5) the two largest phyla are nematodes and arthropods
General characteristics of Arthropods
The appendages of some living arthropod are modified for functions such as walking, feeding, sensory, reception, and defense
(1) segmented bodies: each segment is called a tagmata
- e.g. head, thorax, abodmen, or cephalothorax
(2) have a chitinous skeleton
(3) joined appendages: usually used for locomotion, sensing, feeding
(4) have a reduced coelom
- reduced coelom turns into a body cavity called a hemocoel (like blood travelling through body)
Chelicerates
Chelicerate synapomorphy defines this clade
[Sea spiders, [horseshoe crabs, [[daddy longlegs, mites, ticks], [scorpions, spiders]]]]
The body plan has 2 tagmata
(1) cephalothorax: lack antennae, have eyes
(2) abodmen: 6 pairs of appendages to move
- 1 is modified (chelicerate)
Subphylum Chelicerata
(1) chelicerates, subphylum chelicerata, are named for clawlike feeding appendages called chelicerae
(2) have hemolymph instead of blood; so harvested for medical purposes
- have a pigment called hemocynanin
- cell type called amoebocyte
- can be used on humans to detect and deregulate toxins
(3) most modern cheliceriforms are arachnids, which include spiders, scorpions, ticks, and mites
Chelicerates - arachnid anatomy
(1) have an open circulatory system: dont have vessels
(2) silk gland is joined by spinnerets
(3) book lung that looks like gills
See image
Phylogeny of the major groups of crustaceans
Ostracods, insects, brine shrimp, copepods, barnacles, isopods, shrimp, lobsters, crabs
Subphylum Crustacea
(1) 2 tagmata body plan (cephalothorax, abdomen)
(2) typically have branched appendages that are extensivelt specialized for feeding and locomotion
(3) most crabs are decapod crustaceans
(4) defining synapomorphy of crustacea: 2 antennae
(5) have compound eyes (make images) usually mounted on stocks
(6) 4-6 different mouth parts
(7) reproduce sexually through internal fertilization
- eggs carried by female in abdomen
- when ready to hatch, goes into intertidal zone and eggs are released into water column as larvae
Subphylum Hexapod (insects)
(Lost 1 antennae)
(1) insects and relatives, has more species than all other forms of life combined
(2) undergo metamorphosis from 1 body type to another
- 2 types of insect metamorphosis: hemimetabulous and homometabulous
Hemimetabulous metamorphosis
(1) incomplete
(2) juvenile are called nymphs
- look like/feed exactly like adults but smaller
Holometabulous metamorphosis
(1) complete
(2) distinct larval stage
- larvae and adults live in very different habitats
(3) pupal stage: pupation
- larval body plan is disintegrated then remolded
Nematodes
(1) segmented worms
(2) exoskeleton is called a cuticle
(3) have a pseudocoelom and no appendages
(4) found in most aquatic habitats, in the soil, in most tissues of plants, and in body fluids and tissues of animals
The 4 phyla of deuterostomes
Echinodermata, hemichordata, xenoturbellida, chordata
5 major lineages of echinoderms
Crinoidea (feather stars, sea lillies) , asteroidia (sea stars), ophiuroidea (brittle stars, basket stars) , echinoidea (sea urchins, sand dollars), holothurodea (sea cucumbers)
Synapomorphies of Echinoderms
(1) radial symmetry in adults (larvae are bilaterally symmetric)
(2) endoskeleton of calcium carbonate
(3) water vascular system
Echinoderm Water Vascular System
(1) structure that allows them to move and for tube feet to work
(2) water forma hydrostatic skeleton
(3) madreporite: opening to exterior
(4) ampulla and podium make up tube feet
Feeding habits of echinoderms
(1) mass feeders
(2) suspension feeders
(3) deposit feeders
1 species is predatory
- sticks its tubes into bivalves and cracks
Some can invert their stomach
*all echinoderms have regenerative abilities, sea stars are the best at it
3 lineages of phylum chordata
(1) cephalochordates (lancelates)
(2) urochordates (tunicates)
(3) vertebrates (hagfish, lampreys, sharks, rays, bony fish, amphibians, reptiles, mammals
4 features distinguish the 3 lineages of chordates (at some point in their life cycle)
(1) pharyngeal gill slits
(2) dorsal hollow nerve chord
- runs length of body , neural projections outside of it
(3) notochord
- stiff, flexible rod
(4) muscular, post-anal tail
Urochordates (Tunicates)
Lose nerve chord, notochord, and post-anal tail as adults
Sea squirts and salps (live in deep ocean)
Chordate phylogenetic tree
Vertebrates
(1) dorsal hollow nerve chord becomes a spinal chord
(2) monophyletic group
(3) 2 main synapomorphies
- spinal chord can be made of bone or cartilage (serves as protective structure)
- cranium to protect brain
Vertebrata: Myxinoidea and Petromyzontoidea (jawless vertebrates)
Defense mechanism: slime from skin w numbing agent (makes them slippery)
Lamprey (freshwater) and hagfish (soley marine)
- attatch to things to feed
The Gill-Arch Hypothesis for the evolution of the jaw
(A)jawless vertebrate
(B) intermediate form (basal gnathostomes)
(C) fossil shark
see image
Natural development acted on developing regulatory genes to determine the gill arch morphology
The bigger the predators, need a defense mechanism
Vertebrata - Chondrichthyes
- Sharks, skates, rays
- Most are predators, some are suspension feeders
Defining characteristics: - skeleton made of cartilage (more positively bouyant than bone)
- have paired fins on either side of body
- negatively bouyant
- reproduce sexually
(a) sharks are torpedo shaped
(b) skates and rays are flat
(c) whale shark is a suspension feeder)
Vertebrata - Actinopterygii
Ray-fin fish (any fish we eat is generally a ray fin fish)
(1) have a bony exoskeleton
(2) have a swim bladder: under digestive organs
- suck in air to float, let out to sink
(3) if they have a big mouth, eat other fish, if small mouth, eat zooplankton
(4) bony rods in fin
- dorsal fins are supported by long bony rod
- can be protection
Vertebrate Innovations
Have allowed for vertebrate success and to live on land
(1) vertebrate jaw
(2) tetrapod limb - gain ability to move onto land with 4 legs
(3) amniotic egg - allows egg laying organism to lay eggs on land
(4) placenta
(5) wings and flight
Vertebrata - Actinistia and Dipnoi
- Think this is where the tertrapod limb originated
- Only 8 species but super common in fossil record
- fleshy lobes supprted by bones
Tetrapods (reptiles, amphibians, mammals) have 5 distinguishing characteristics
(1) 4 limbs, feet with digits
(2) neck that allows for isolated movement from head down
(3) fusion of pelvic girdle to backbone
(4) absence of gills
(5) ears
The 3 orders of amphibians
(1) order urodela (salamanders)
(2) order anura (frogs & toads)
(3) order apoda (caecilians) (lost their limbs)
Traits of amphibians
(1) most have adults that feed on land but lay eggs in H2O
(2) gas exchange happens across skin (get O2 through skin)
- have lungs when adult
Amphibian reproductive cycle
Like transitioning from water to land
- need gills as developing
- operculum grows over gills as legs develop
- gills turn into lungs
Derived chracteristics of amniotes
(In amphibians, egg only has a single membrane, but for reptiles the egg laying mammals egg has a hard shell and extra layer of water to be on land)
- But the animals have to be able to breathe air so shell has tiny holes in CaCO3 structure…blood vessels from embryo grow and press up against shell to get O2
(While this is happening, lungs are developing)
Parts of amniotic egg
(1) Embryo
(2) yolk sac: contains nutrients
(3) allantois: contains waste of embryo
(4) amnion: contains embryo
(5) provides water and mechanical support
(6) shell
Reptiles
(1) monophyletic group
(2) includes tuataras, lizards, snakes, turtles, crocodilians, birds, and the extinct dinosaurs
(3) have scales made of keratin that create a waterproof barrier
(4) most lay shelled eggs on land
(5) have adapted to terrestrial life)
(6) always have lungs
(7) most are ectothermic (derive heat from environment) , not birds
Birds
(1) endothermic Derived traits for flight - dont have scales, but have wings with keratin feathers - lack a urinary bladder - females only have 1 ovary - lots of teeth - holey bones
Mammals have:
(1) mammary glands which produce milk
(2) hair
(3) high metabolic rate, due to endothermy
(4) larger brain than other vertebrates of equivalent size (doesnt mean more intelligent)
(5) differentiated teeth (canines, molars, teeth that have different functions)
Mammals have ___ clades
3: monotremes, marsupials, eutherians
Monotremes
Platypus, echidna
- most ancient group of living mammals
- egg-laying mammals
- very low metabolic rate, maybe because not using energy for placental development
- low body temp
Marsupials
Kangaroos, opposums, koalas, wallabees, etc
- females have a placenta
- young are born very poorly developed (short embryonic period)
- rest of development happens when embryo is attatched to nipple of mom
Eutheria - “placental mammals”
Primates, rodents, bats, carnivores
- full internal fertilization
- placental growth
- moms feed offspring after they are born
Bacteria and Archaea both have a ___ cell type
Prokaryotic
Key synapomorphies of Bacteria, Archaea, Eukarya
Bacteria: peptidoglycan in cell wall
Archaea: archaeal-type plasmal membrane
Eukarya: nuclear envelope (genetic material is wrapped)
The evolution of the eukaryote group involved 2 processes:
Compartamentalization and endosymbiosis
Compartamentalization
Development of nuclear envelope
Endosymbiosis
2 separate events that resulted in addtional organelles for eukaryotes: theory of how organelles developed (mitochondria, chloroplasts)
- A symbiotic relationship developed between an ancestral aerobic heterotrophic bacterial prokaryote (not archaea) and a eukaryotic cell
- This energy-producing aerobic prokaryote took up residence inside the engulfing eukaryotic cell and was NOT destroyed
- This energy-producing aerobic prokaryote eventually became the mitochondrian
- Eventually some of the genes from the mitochondrian were relocated to the nucleus, but other genes remained (mitochondrial DNA)
- Humans inherit their mothers DNA since only the nucleus of a sperm fertilizes a human egg
What is a prokaryotic cell?
- a simple, single-celled organism that lacks a nucleus and membrane-bound organelles (no compartamentalization)
- consist of a single open space on the inside, instead if beinf divided up by membrane walls
- majority of prokaryotic DNA is found in a central region of the cell called the nucleoid, and it typically consists of a single loop called a circular chomosome
- very small: typical prokaryote cells range from 0.1 to 5.0 micrometers in diameter and are significantly smaller than eukaryotic cells
Protists
(The informal name of the group of mostly unicellular eukaryotes) (all eukaryotes that arent land planta, fungi, or animals)
- paraphyletic group
- no defining synapomorphies, but usually live in H2O environment
- have economic, medical, ecological importance
- transition group: studied to study evolution of land plants and fungi
- very small
Structural and Functional Diversity in Protists
(Nutritional diversity of protists)
- Photoautotrophs: contain chloroplasts, take in sunlight to make carbon
- Heterotrophs: absorb organic molecules, or ingest larger food particles
- Mixotrophs: combine photosynthesis and heterotrophic nutritionn
How do protists move?
- Amoeboid motion via pseudopodia (limbs)
- Swimming via flagella: single flickering tail to propel themselves
- Swimming via cilia
Dinoflagellates
- Have 2 flagella
- Each cell is reinforced by cellulose plates
- Very small protists
- Medically and ecologically problematic: responsible for red tide
- red tide bloom blocks oxygen from entering water colunm: toxic fish wash up (have ingested the dinoflagellates)
- the massive die offs create diversity problemj
Apicomplexans
- Parasites of animals and some cause serious human disease (e.g. plasmodium causes malaria
- Spread through their hosts as infectious cells called sporozites
- The apical end is the problematic end
Plasmodium
The apicomplexpum that causes malaria
- evolves too fast for vaccine and drugs
- has a two-host life cycle: humans and mosquitos
Life cycle of Plasmodium (human part)
- Enter from mosquito as sporozoites
- Sporozoites enter heptatocytes (liver cells) and become merezoites which use their apical complex to penetrate and colonize RB
- Merezoites divide asexually in RBC and break out in large numbers, causing fever, chills
- The merezoites form gametes
Life cycle of plasmodium in mosquitos
- A mosquito bites an infected human and picks up plasmodium gametocytes (gametes form from gametocytes)
- In mosquitos digestive tract, fertilization occurs and a zygote forms
- An Oocyst develops from the zygote in the wall of the mosquitos gut
- The Oocyst release 1000s of sporozoites which migrate to mosquitos salivary gland
Protists play key roles in ecological communities:
- Found in diverse aquatic environments
- Often play the role of symbiont or producer
- about 30% of photosynthesis on our planet is due to photosynthetic protists found near the top of the water column
Why was the evolution of the mesoderm important?
It gave rise to the first complex muscle tissue used in movement
Coelom
An enclosed, fluid-filled body cavity between the “tubes”
