Biology II

Chapter 27

Heterotrophy

Obtain energy and organic molecules by ingesting other organisms

Herbivores

Consume autotrophs

Carnivores

Consume heterotrophs

Omnivores

Consume both autotrophs and heterotrophs

Detritivores

Consume decomposing organisms

Invertebrates

No backbone

Vertebrates

Has a backbone

Asymmetrical

Grows as an irregular mass

Symmetrical

Definite shape along an axis

Radial Symmetry

It parts are arranged in such a way that any longitudinal plane passing through the central axis divides the organism into halves that are approximately mirror images (jellyfish)

Bilateral Symmetry

The body has right and left halves that are mirror images of each other (humans)

Cephalization

The evolutionary trend in bilateral animals is that nervous tissue, sense organs, and feeding structures concentrate at the anterior (front) end, forming a distinct head. This adaptation improves environmental sensing, enables faster reactions, and aids in hunting or foraging. It is highly developed in arthropods, mollusks, and vertebrates.

Ectoderm

Outer layer

Endoderm Layer

The inside layer and give rise to the digestive system

Mesoderm Layer

Middle layer, muscles and skeleton

Pseudocoelom

An invertebrate animal with a "false" body cavity (pseudocoel) that is only partially lined by mesodermal tissue, separating the mesoderm and endoderm. These triploblastic, often worm-like organisms use this fluid-filled cavity as a hydrostatic skeleton for movement and support

Coelom

A cavity that develops entirely within the mesoderm

Circulatory System

A network of vessels that carry fluids to and from the body, distant from the sites of digestion (gut) and gas exchange

Open Circulatory System

Blood passes from vessels into sinuses, mixes with body fluid that bathes the cells of tissues, then reenters vessels in another location

Closed Circulatory System

The blood is entirely faster and more efficient than it is through an open system