CH 32: Animal Diversity Overview

Flashcards on Animal Diversity

Define an animal.

A living creature that obtains nutrients by capturing and consuming other organisms (consumers and heterotrophs).

Describe cell structure and cell specialization of animals.

After a sperm fertilizes an egg, rapid cell division called cleavage occurs, forming a multicellular, hollow ball known as a blastula, which contains a fluid-filled cavity called the blastocoel. The blastula then undergoes gastrulation, a process where the layers of embryonic tissues form, resulting in a gastrula.

What are the 3 germ layers? Which layers give rise to the major organ systems?

• Ectoderm: The outer layer covering the embryo's surface; gives rise to the epidermis and nervous system.
• Endoderm: The innermost layer lining the developing digestive tube (archenteron); forms the lining of the digestive tract and associated organs.
• Mesoderm: The middle layer found only in triploblastic animals; develops into muscles, and most other organs between the digestive tract and the outer covering of the animal.

Describe animal development, including cleavage, a blastula, blastocoel, gastrulation and a gastrula.

Animal development includes cleavage, blastula formation, gastrulation, and organogenesis, leading to a larva and then a juvenile.

What are Hox genes and why are they relevant to animal evolution?

Hox genes are a set of genes that control an animal's body plan. They are highly conserved and play a crucial role in the development of animal body structures. Changes in Hox genes can lead to significant evolutionary changes in body form.

Define larva and metamorphosis.

A larva is a sexually immature and morphologically distinct form of an animal that undergoes metamorphosis to transform into a juvenile or adult. Metamorphosis is the process of transformation from a larva to an adult form.

What is a choanoflagellate? What was their role in the development of animals?

A choanoflagellate is a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals. They likely represent the ancestral protist from which animals evolved.

Review the role of cadherin in cell to cell adhesion.

Cadherin is a protein needed for cell adhesion and cell communication, playing a key role in holding cells together and facilitating interactions between cells.

What does the term Ediacaran biota refer to? What organisms do we include with this biota?

The Ediacaran biota refers to early members of the animal fossil record, representing some of the earliest evidence of animal life. Organisms included lack hard shells or skeletons, and are found in late Proterozoic rocks.

Briefly answer the following questions about the history of animals; What is the age of the oldest animal fossils?
What is the Cambrian explosion and what sorts of animals (and animal traits) are represented from Cambrian era fossils?
When did mammals begin to replace dinosaurs as the main large herbivores & predators?

• Oldest animal fossils: The Ediacaran biota represents some of the earliest fossils.
• Cambrian explosion: Marks the earliest fossil appearance of many major groups of living animals.
• Mammals replacing dinosaurs: Mammals began to diversify and replace dinosaurs as the dominant large herbivores and predators after the Cretaceous-Paleogene extinction event, approximately 66 million years ago.

Be able to explain what a body plan is and discuss examples as presented in lecture

A body plan refers to the overall structure and organization of an animal. Examples include bilaterally symmetric vs radially symmetric animals.

Compare the two types of body symmetry.

• Bilateral symmetry: Body plan with a left and right side that are mirror images (e.g., Bilaterians).
• Radial symmetry: Body plan where body parts are arranged around a central axis.

Define tissues and briefly describe the three embryonic germ layers.

Tissues are groups of similar cells that act as a functional unit. The three embryonic germ layers are ectoderm, mesoderm, and endoderm.

Be able to distinguish between coelomates, pseudocoelomates and acoelomates.

• Coelomates: Animals with a true coelom (body cavity).
• Pseudocoelomates: Animals with a body cavity derived from the blast