BIO 2200 Unit 3 & 4

Asymmetrical

No defined symmetry

• Sponges

Radial

Suited for sessile or drifting lifestyles

• Cnidirians

Bilateral symmetry

Supports directed movement and complex behavior

• Chordates, molluscs

Three main ways aquatic animals acquire oxygen?

Diffusion, gills, and lungs (in some vertebrates)

What adaptations aid movement in a viscous environment?

• Streamlined bodies

• Specialized structures: fins & jet propulsion

What is the primary feeding method of sponges?

Filter feeding through pores

• Diffusion for nutrient transport

What distinguishes cnidarians from sponges?

Cnidirians have radial symmetry and true tissues

Radula

A scraping, grazing, or chewing organ used by gastropods

Bivalves

• no distinct head

• filter feeders

• use gills to breathe and feed

• Ex. clams

How do cephalopods move quickly through water

Jet propulsion by expelling water from their mantle cavity

Four key traits of all chordates

Notochord, dorsal hollow nerve cord, pharyngeal slits/clefts, and post-anal tail

What distinguishes lancelets as basal chordates

retain all chordate traits into adulthood, filter feeders

Notochord

• present in all chordate embryos, and remain in some adults

• longitudinal, flexible rod derived from mesoderm

• provides skeletal support —> animals that lack a spine

pharyngeal clefts and slits

• arches along the pharynx that develop into slits

pharyngeal clefts and slits in invertebrates

suspension feeding, pulling water over pharyngeal slits and filter out microparticles

pharyngeal clefts and slits in aquatic vertebrates

become gills —> oxygen acquisition and respiration

pharyngeal clefts and slits in tetrapods

no slits in adults, slits become other parts of the head

Dorsal hollow nerve cord

• Derived from ectoderm —> found closer to the outside of the body

• Hollow tube that develops into the central nervous system

Post-anal tail

• Muscular

• reduced in some adult chordates

  • Ecx. cats and dogs still have distinctive feature

What happens to the post-anal tail in non-chordates

Tail ends where the digestive tract runs the body length

How do tunicates change from larvae to adults

Larvae display chordate traits, adults become sessile and lose most traits

What makes hagfish and lampreys unique among vertebrates?

They lack jaws and a true spine but have a rudimentary vertebrae

• Incomplete form of vertebrae

Why is the evolution of jaws significant in vertebrae evolution

Allowed for a braoder diet, promoting adaptive radiation

What major event created major aquatic diversity and predation

The Cambrian Explosion (535-525 MYA)

What is the closest living relative to land plants

Charophytes (type of green algae)

What traits do plants share with Charophytes

• Chloroplasts with chlorophyll a & b

• Protein rings for cellulose

• Flagellated sperm

• Phargrmoplast: unique structure during cell division

Why did plants move from water to land?

• More light

• CO₂ and O₂

• Nutrients and soil

• Open habitats

• Low competition

What were the major challenges for plants moving to land

• Desiccation

• UV damage

• Accessing nutrients

• Oxygen intake

• Reproduction

What adaptations helped prevent water loss

Waxy cuticle and stomata for gas exchange

What compound protects plants from UV damage

Flavanoids —> plant sunscreen

Mycorrhizae

A symbiotic relationship between fungi and plant roots that helps absorb water and nutrients

How do land plants protect their embryos

Through maternal tissues that surround and nourish the embryo

Alternation of generations

Multicellular diploid and haploid stages in the plant life cuucle

Characteristics of non-vascular plants

• No vascular tissue

• Limited height

• Rhizoids (anchors)

• Require water for sperm movement

• Reproduce via spores

What limits the size of nonvascular plants

Lack of vascular tissue and reliance on diffusion for water/nutrients

What distinguishes seedless vascular plants

• Xylem

• Phloem

• Lignin

• Roots and leaves

• Greater height and nutrient transport

Xylem

Carries water, water-conducting cells

Lignin

Provides structural support

Phloem

carries nutrients, distributes sugars, amino acids

What is the dominant life stage in seedless vascular plants

Diploid sporophyte

Key innovations in seed plants

• Seeds

• Pollen

• Enclosed spores

• Vascular tissue

Why are seeds advantageous?

• Protect the embryo

• Allow for long-distance dispersal

• Survive in harsh conditions

Pollen

A structure that contains the male gametophyte, allows for fertilization without water, increases genetic diversity

How do angiosperms differ from gumnosperms

Angiosperms have flowers and fruits, while gymnosperms do not

Fruit

A mature ovary that protects and helps disperse seeds

How do flowers and fruit increase plant fitness

Flowers attract pollinators, fruits attract dispersers, enhancing reproduction adn dispersal success

Why do seed plants have greater diversity than seedless plants

• More effective dispersal

• Increased genetic recombination via pollen

• Broader environmental adaptability

Why did ancient seedless vascular trees turn into coal?

Decomposers for lignin and cellulose hadn’t evolved yet, so the trees didn’t fully decay

How do fungi benefit plants in mycorrhizae relationships?

Increase surface area nad help absorb difficult-to-access nutrients

What do plants give fungi in mycorrhizae mutualisms

Carbohydrates produced via photosynthesis

How does pollination represent plant-anima mutualism?

Animals transfer pollen, increasing reproduction, while also gaining food in return

How do animals help with seed dispersal

Animals eat fruits and later defecate seeds, spreading them and providing natural fertilizer

Herbivory

When animals eat plants, damaging or killing them, this reduces reproductive success

What are the three major plant defense strategies against herbivory?

Physical defenses, chemical defenses, and mutualisitc bodyguards

What evolutionary process is driven by plant-animal interactions

Coevolution, mutual adaptations between plants and animals over time

What adaptation helps reduce water loss and provides UV protection in land animals?

An exoskeleton

Why did animals shift to internal fertilization on land

To protect gametes from drying out since water is not present to transport sperm

Arthropod

“Jointed foot”, paired, jointed appendages

What is the arthropod exoskeleton made of?

Chitin, sometimes strengthened with protein or calcium carbonate

How do arthropods grow if their exoskelton is rigid

Molting, shedding of the old exoskeleton

What kind of circulatory system do arthropods have?

An open circulatory system with hemolymph flowing through the hemocoel.

How do insects breathe?

Through a tracheal system: tubes that deliver oxygen directly to tissues.

How do chelicerates breathe?

Book lungs: folded tissues surrounded by hemolymph

Three types of non-insect arthropods

Chelicerates, myriapods, and crustaceans

What makes insects the most diverse animal group

• 6 legs

• Flight

• Metamorphisis

• Diverse mouthparts

Incomplete metamorphisis

Young resemble adults

Complete metamorphisis

Larvae and adults are distinct

What ecosystem services do beneficial insects provide?

• Pollination

• pest control

• decomposition

What major innovation triggered the rapid diversification of vertebrates

The evolution of jaws

What is the hypothesized origin of vertebrate jaws?

Jaws evolved from skeletal rods that supported gill slits.

Which group was the first to evolve jaws and mineralized teeth?

Sharks

What is unique about the shark skeleton

It is made of cartilage, a derived trait

• Loss of mineralization

What are ray-finned fishes known for evolutionarily?

First fully mineralized skeleton and the swim bladder.

From what structure did the swim bladder evolve?

Lungs

What features define lobe-finned fish like coelacanths and lungfish?

Fins with bones resembling wrists, support for movement on land.

Why is Tiktaalik a transitional fossil?

It had wrist bones, a neck, rib cage, and a large pelvis, but was still aquatic

Tetrapods

Vertebrates with four limbs

• Amphibians, reptiles, birds, and mammals

What adaptations helped tetrapods survive on land

• Limbs with digits

• Fused pelvic girdle

• Lungs

• Skin that resists water loss

Why did tetrapods need stronger skeletal support on land

To counter gravity without bouyany water support

What replaced gills as the main gas exchnage system in land vertebrates?

Lungs and skin in some amphibians

What life stage do amphibians usually spend in water?

The larval stage

• Tadpoles

How does amphibian metamorphosis change their anatomy

They develop legs, lungs and complex organs

Why do amphibians live in moist environments?

Skin-based gas exchange and external fertilization

What adaptation allows reptiles to reproduce fully on land?

Shelled eggs and internal fertilization

What is the function of keratinized scales or feathers in reptiles

To prevent water loss

Ectotherm reptiles

Snales, lizards, and turtles

Endotherm reptiles

Birds

What is a trait only turtles have among reptiles?

Their shell is fused to their vertebrae and is not removable

What is the adaptive advantage of the amniotic egg?

Allows embryos to develop a self-contained, water conserving environment which is crucial for life on land

Amnion

Cushions the embryo in fluid

Yolk sac

Provides nutrients

Allantois

Stores meatbolic waste

Chorion

Enables gas exchange

What other adaptations are found in amniotes?

• Less permeable skin

• Rib cage ventilation (lungs)

• Internal gestation or shelled eggs to prevent water loss

Derived traits of mammals

• Mammary glands

• Hair

• Fat layer

• Endothermy

• Large brains

• Extended parental care

• Varied teeth

Monotremes

lay eggs and lack nipples

• Milk is secreted through skin pores

Marsupials

Complete their development in a pouch after brief gestation

Eutherians

Longer internal gestation with complex placentas

Key derived traits of primates

• Grasping hands/feet

• Flat nails

• Large brains

• Short jaws

• Forward facing eyes

• Opposable thumbs (in some)

Hominins

• Bipedalism

• Reduced jaw/teeth size

• Shorter digestive tracts

• Larger brains (complex thought and tool use)