Lecture 02 January 08 2025 jp

What defines an animal biologically?

All members of the kingdom Animalia, also known as Metazoa.

What are the key characteristics of animals?

Multicellular eukaryotes without a cell wall, heterotrophic, motile at some stage, and capable of asexual or sexual reproduction.

What is the estimated number of known animal species on Earth?

More than 1 million.

What does it mean that the kingdom Animalia is monophyletic?

All animals share a single common ancestry.

What type of ancestor do biologists believe the first animals evolved from?

A colonial flagellated protist.

What type of cell is a choanocyte related to?

Similar to choanoflagellate cells.

How many recognized animal phyla are there?

Approximately 35.

What is the primary function of the extracellular matrix in animals?

To provide tissue stability.

What distinguishes animal cells from plant cells?

Animal cells lack cell walls and contain centrioles and lysosomes.

What evidence supports the evolutionary origins of animals?

Morphological and molecular evidence from modern colonial flagellated species.