Animal Evolution and Diversity

A collection of flashcards covering key concepts and definitions related to animal evolution and diversity based on lecture notes.

What do phylogeny charts illustrate?

They illustrate the evolutionary relationships among more than a million animal species.

Which groups are included in the earliest branches of the animal tree?

Sponges, cnidarians, ctenophores, and placozoans.

What are bilaterians and what are their main characteristics?

Bilaterians are animals that have bilateral symmetry and develop from three germ layers.

What distinguishes vertebrates from other animals?

Most vertebrates have a bony cranium and a vertebral column.

When did animals first evolve?

Animals first evolved more than 600 million years ago in the oceans.

What is the primary habitat of most animal species today?

Today, most animal species are found on land.

How do sponges gain nutrition?

Sponges gain nutrition by intracellular digestion, capturing food particles through endocytosis.

What is a defining feature of cnidarians?

Cnidarians exhibit radial symmetry and have stinging cells for predation.

How do ctenophores differ from cnidarians?

Ctenophores propel themselves using coordinated cilia and have an anal pore for waste elimination.

What defines protostomes in terms of embryonic development?

In protostomes, the blastopore becomes the mouth.

What are the two major groups of bilaterians?

The two major groups are protostomes and deuterostomes.

What is a key characteristic of lophotrochozoans?

Lophotrochozoans include diverse animal phyla like mollusks and annelids.

What unique features do cephalopods have?

Cephalopods possess muscular tentacles and a jet propulsion system for rapid movement.

How do bivalves filter food?

Bivalves filter food by drawing water through their siphons and trapping particles.

What is the primary characteristic of Ecdysozoans?

Ecdysozoans undergo ecdysis, or molting of their external cuticle.

What role do nematodes play in ecosystems?

Nematodes are numerous and often occur in diverse environments, including as parasites.

What evolutionary feature defines insects?

Insects are characterized by their wings, which evolved about 350 million years ago.

What adaptations do amniotes have for life on land?

Amniotes have a desiccation-resistant shell and specialized membranes for gas exchange.

How are marsupials different from placental mammals?

Marsupials give birth to underdeveloped young that must develop in a pouch, while placental mammals have a placenta for nourishment.

What feature is unique to vertebrates?

Vertebrates have a jointed skeleton made of vertebrae.

What adaptations do bony fish have for survival?

Bony fish have moveable jaws, swim bladders for buoyancy, and kidneys for water balance.

What distinguishes amphibians from other vertebrates?

Amphibians have distinct life cycles with both aquatic larvae and terrestrial adult forms.

What major evolutionary pattern is observed in life forms over time?

There is a pattern of increasing complexity and specialization, leading to greater species diversity.

What role do bacteria and archaea play in ecosystems?

They remain integral to functioning ecosystems despite the evolution of more complex eukaryotes.

Deuterostomes

A major group of animals characterized by the developmental fate of the blastopore, which becomes the anus; includes humans and chordates.

Hemichordata

Includes 75 species of acorn worms that utilize pharyngeal slits and possess dorsal nerve cords.

Echinodermata

Comprise 7000 species known for their unique fivefold symmetry and interlocking plate skeletons; possess a water vascular system.

Chordata

Comprises vertebrates with key traits including pharyngeal slits, notochord, and nerve cord.

Cephalochordates

Ancient lineage within Chordata with body plans showing links to vertebrates but lacking complex structure.

Tunicates

Filter-feeding animals with a unique adult form and share early developmental traits with vertebrates, suggested as humans’ closest invertebrate relatives.

Vertebrates

Characterized by a jointed skeleton, cranium, and complex body systems; divided into groups like jawless fish, cartilaginous fish, and bony fish.

Fish Evolution

Fish comprise diverse lineages with hagfish and lampreys forming foundational elements of vertebrate evolution.

Amphibians

Transition creatures exhibiting both aquatic larval stages with gills and terrestrial adult forms with lungs.

Amniotes

Defined by the evolution of an amniotic egg, enabling reproduction away from water; includes reptiles, birds, and mammals.

Mammals

Animals characterized by hair and mammary glands for nurturing offspring; exhibit significant evolutionary diversity including monotremes, marsupials, and placental mammals.

Evolution Complexity

Illustrates a pattern of increasing complexity and accumulation over time, demonstrating that simple forms remain integral to modern ecosystems.