Animals

What is the estimated range of animal species existing on Earth today?

Between 3 million and 10 million animals.

How many species have been described to date?

1.4 million species.

What is the closest living relative to animals?

Choanoflagellates.

What key traits define the monophyletic clade of animals?

Multicellular eukaryotes, no cell walls, heterotrophs, and ability to move at some point in life cycle.

What is the prevailing hypothesis about the most ancient lineage of animals?

Sponges are the most ancient lineage of animals.

What types of data are used to understand animal evolutionary relationships?

Fossils, comparative morphology, comparative development, and comparative genomics.

What characteristic defines diploblasts?

Embryos have two types of tissues or germ layers.

What are the three germ layers in triploblasts?

Ectoderm, endoderm, and mesoderm.

What is the significance of mesoderm in triploblasts?

It develops into distinct adult tissues and organs.

What defines the body symmetry of most animals?

Bilateral symmetry, with a single plane of symmetry.

How does radial symmetry differ from bilateral symmetry?

Radial symmetry has multiple planes of symmetry, while bilateral symmetry has one.

What type of body shape do bilaterians typically have?

Tube within a tube.

What is a coelom?

An enclosed, fluid-filled body cavity between the tubes.

What are true coelomates?

Animals whose coelom is completely lined with mesoderm.

What distinguishes protostomes from deuterostomes?

Protostomes develop the mouth before the anus, while deuterostomes develop the anus before the mouth.

What is segmentation in animals?

Division of the body into a series of similar structures.

What feeding strategy do detritivores use?

Feed on dead organic matter.

What type of feeders capture food by filtering particles?

Suspension feeders.

What is a key aspect of cephalization?

Concentration of sensory organs in the head region.

How do endoparasites differ from ectoparasites?

Endoparasites live inside their hosts while ectoparasites live outside.

Which animals are classified as heterotrophs?

Animals that obtain nutrients from other organisms.

What distinguishes mass feeders from other feeding types?

Mass feeders take chunks of food into their mouths.

How have some animals adapted through convergent evolution?

They achieve functional similarity through independent evolutionary paths.

What type of symmetry is commonly seen in cnidarians?

Radial symmetry.

What regulates the development of the anterior-posterior axis in bilaterians?

Hox genes.

What role do transcription factors play in developmental biology?

They help find patterns in gene expression that cause morphological changes.

What do sponges lack that complex organisms have?

Complex tissues organized into structural and functional units.

What type of feeding occurs at the cellular level in sponges?

Feeding with choanocytes trapping organic debris.

What is the function of muscle cells in animals?

Change shape of the body by contracting.

How do adaptations relate to feeding strategies among animals?

Animals with similar body plans may have different feeding strategies based on their niche.

What is an example of an omnivore?

Humans, as they feed on plants, animals, fungi, and more.

How does the evolutionary flexibility of the coelom affect its classification?

It has reduced its usefulness as a synapomorphy for bilaterian animals.

What are some specialized cell types found in sponges?

Cells that are dependent on each other, organized in layers surrounded by extracellular matrix (ECM).

What evidence supports the idea that sponges might be paraphyletic?

Sponges contain some but not all descendants of the common ancestor.

What is a defining characteristic of vertebrates?

Segmented backbone.

How do animals' nervous systems relate to their body symmetry?

No symmetry in sponges; radially symmetrical organisms have a nerve net, while bilaterally symmetric organisms have a CNS.

What is a defining characteristic of vertebrates?

Segmented backbone.

what is the term for the group containing fungi and animals?

opisthokonta

animals are most closely related to?

choanoflagellates

porifera are?

sponges

who are benthic and sessile?

sponges and choanoflagellates

benthic meaning?

live at bottom of aquatic enviro

sessile meaning?

adults permanently attached to substrate and cannot move freely

what groups are diploblasts?

ctenophores and cnidaria

What is the Cambrian Explosion?

A period around 541 to 530 million years ago during which most major animal phyla and body plans appeared in the fossil record

What are the three types of skeletal systems that enable complex movements in animals?

Hydrostatic skeletons (flexible support), endoskeletons (internal rigid support), and exoskeletons (external rigid support).

What are the functions of animal locomotion?

Finding food, finding mates, escaping from predators, and dispersing to new habitats.

What are the ways in which animals move?

Animals can burrow, slither, swim, fly, crawl, walk, or run.

What are the three types of skeletal systems in animals?

Hydrostatic skeletons (flexible body wall), Endoskeletons (internal structures), and Exoskeletons (external armor).

What are the three reproductive strategies in animals?

Viviparous (live-bearing), Oviparous (egg-bearing), and Ovoviviparous (egg-live-bearing).

What is metamorphosis in animal life cycles?

A drastic change from larvae to juveniles, which look like adults and live in the same habitats.