Animal Characteristics, Evolution, and Biodiversity Conservation

What are the key shared characteristics of all animals?

Eukaryotic, multicellular, lack cell walls, heterotrophic with internal ingestion, capable of movement at some life stage, and possess nerve/muscle cells and sensory systems.

Which group has the highest species richness and abundance?

Arthropods.

What are the five levels of metazoan organization?

Protoplasmic, Cellular, Tissue, Tissue-Organ, Organ-System.

What are the major symmetry types in animals?

Asymmetrical, radial symmetry, bilateral symmetry.

What lifestyle is associated with radial symmetry?

Sessile or sedentary animals facing environment from all sides.

What adaptations arise with bilateral symmetry?

Cephalization, directional movement, specialized sensory systems.

What germ layers do diploblasts have?

Ectoderm and endoderm.

What do triploblasts have that diploblasts lack?

Mesoderm — enabling muscles, organs, and tract digestion.

What is a coelom and its functions?

A fluid-filled body cavity allowing organ development, diffusion surfaces, storage, hydrostatic skeleton, and larger body size.

What is metamerism?

Serial repetition of body segments along the longitudinal axis.

Name major trends in animal evolution.

Increased size/complexity, move from filter-feeding to active predation, specialization of tissues, improved sensory/locomotor systems, land adaptations like cuticles and exoskeletons.

What distinguishes protostomes from deuterostomes?

Different gastrulation patterns for making the gut; protostomes form mouth first, deuterostomes form anus first.

What do HOX genes regulate?

Embryonic body patterning, timing/location of body part development.

Key traits of echinoderms?

Marine, endoskeleton of ossicles, water vascular system, tube feet, bilateral larvae, pentaradial adults.

Key traits of hemichordates?

Marine, bilateral, gill pores, proboscis, filter feeders, triploblastic coelomates.

What are the five chordate synapomorphies?

Notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail, endostyle/thyroid gland.

Key difference between tunicate larvae and adults?

Larvae possess all chordate features; adults lose notochord, tail, and reduce nerve cord.

Traits of hagfish and lampreys?

Jawless, scaleless, finless, cartilaginous skulls; hagfish are scavengers, lampreys are parasites.

What major innovations define vertebrates?

Living endoskeleton, efficient respiration, advanced nervous system, paired limbs.

Key traits of jawed fish?

Jaws, skulls, vertebrae, fins, gills, hydrodynamic bodies.

Why are amphibians considered the first land tetrapods?

They have limbs, lungs, and can partially live on land but rely on water for reproduction.

List terrestrial challenges for early tetrapods.

Body support, desiccation, temperature fluctuations, respiration changes.

What defines amniotes?

Amniotic egg with amnion, chorion, allantois, and yolk sac; reproduction independent of water.

Key reptile adaptations?

Internal fertilization, rib ventilation, scales/feathers, improved sensory systems.

What adaptations enable flight?

Feathers, beaks, specialized lungs, light skeleton, strong vision, 4-chambered heart.

What are defining mammalian traits?

Hair, mammary glands, endothermy, specialized teeth, complex brains, placenta (in eutherians).

What traits distinguish hominids?

Tool use, large brain, smaller jaw, communication, bipedalism in Homo sapiens.

Did humans evolve from chimpanzees?

No — humans and chimps share a common ancestor 6-8 million years ago.

What evidence shows gene flow between Neanderthals and humans?

Modern human genomes contain Neanderthal DNA affecting height, immunity, and disease susceptibility.

What are the three types of biodiversity?

Species diversity, genetic/phylogenetic diversity, ecosystem/functional diversity.

Why do biodiverse communities recover better from disturbances?

They show higher resistance and resilience due to functional redundancy and genetic variety.

What are major global threats to biodiversity?

Habitat loss, overexploitation, invasive species, pollution, climate change.

What is the shifting baselines concept?

Generational change in what is considered 'normal' ecosystem conditions, often masking declines.

What does 'functionally extinct' mean?

A species' abundance is so low it no longer plays its ecological role.

What are ecosystem services?

All direct and indirect benefits humans receive from ecosystems; valued at ~$125 trillion/year.

What are biodiversity hotspots?

Areas with extremely high endemism and severe habitat loss.

What are ecoregions?

Distinct ecological areas defined by species, climate, and ecosystems.

What does endemic mean?

Species found only in a specific geographic location.

What is the purpose of IUCN protected area categories?

Standardize conservation strategies by level of protection and land use restrictions.

What is the Anthropocene?

A human-dominated geological era characterized by major landscape modification (deforestation, mining, urbanization).

What ethical arguments support biodiversity conservation?

Intrinsic worth of organisms, responsibility for environmental damage, and obligation to future generations.