Invertebrate Biology Characteristics and Phyla

A subphylum of arthropods characterized by a single pair of antennae, mandibles, and a body divided into segments. Most uniramians are terrestrial.

Terrestrial arthropods with a long segmented body, one pair of legs per segment, and venomous claws for hunting.

Terrestrial arthropods with a long segmented body, two pairs of legs per segment, and mostly herbivorous diet.

A class of insects with three body segments (head, thorax, abdomen), three pairs of legs, and often wings.

A process by which insects undergo significant physical changes during their development. It can be complete or incomplete.

A type of symbiosis where both organisms benefit from the relationship.

A type of symbiosis where one organism benefits, while the other neither benefits nor is harmed.

A type of symbiosis where one organism benefits at the expense of the other.

Animals are eukaryotic, multicellular, heterotrophic organisms that lack cell walls. They are divided into two groups: invertebrates (no backbone) and vertebrates (backbone).

The 8 invertebrate phyla are: Porifera (sponges), Cnidaria (cnidarians), Platyhelminthes (flatworms), Nematoda (roundworms), Annelida (segmented worms), Mollusca (mollusks), Arthropoda (arthropods), and Echinodermata (echinoderms).

Cell specialization, early development, body symmetry, cephalization, and body cavity (coelom) are important trends in the evolution of animals.

Cell specialization refers to the process where cells develop specialized functions and structures. In animals, three germ layers (ectoderm, mesoderm, and endoderm) give rise to all the different cell types.

In protostomes, the blastopore develops into the mouth, whereas in deuterostomes, the blastopore becomes the anus. Most invertebrates are protostomes, while echinoderms and vertebrates are deuterostomes.

Asymmetry, radial symmetry, and bilateral symmetry are the three types of body symmetry found in animals. Asymmetry means no plane of symmetry, radial means multiple planes, and bilateral means one plane.

Cephalization is the evolutionary trend towards a concentration of nerves and sensory organs in the anterior (head) region of the body. It allows for more efficient processing of information and response to stimuli.

A coelom is a fluid-filled body cavity that contains the internal organs. Animals can be classified into three types based on their coelom: acoelom (no body cavity), pseudocoelom (false body cavity), and coelom (true body cavity).

Phylum Echinodermata includes spiny-skinned marine invertebrates such as starfishes, sea urchins, and sea cucumbers. These organisms exhibit radial symmetry, a water vascular system for locomotion and feeding, and a unique endoskeleton made of calcium carbonate plates.

A water vascular system is a unique hydraulic system present in echinoderms. It consists of interconnected canals filled with fluid that operate tiny tube feet, which are used for locomotion, feeding, and sensory functions.

Sea stars are star-shaped, carnivorous echinoderms that inhabit the ocean floor. They feed on mollusks, crustaceans, and other invertebrates. Their mouth is located on their underside, and they possess a central disc with five or more radiating arms.

Brittle stars are echinoderms characterized by their small body disc and five or more long, flexible arms. They are typically filter feeders or scavengers, using their arms to collect food particles.

Sea urchins are echinoderms with spherical bodies covered in spines for protection and locomotion. They are primarily herbivores, feeding on algae and detritus. They lack arms but possess a complex system of teeth for chewing.

Sea cucumbers are elongated, leathery echinoderms with tentacles surrounding their mouths. They are primarily detritus feeders, consuming organic matter from the ocean floor. Their endoskeleton is reduced and embedded in the body wall.

The exoskeleton is a hard, external covering that provides support, protection, and attachment for muscles. It is found in arthropods like insects, crabs, and lobsters.

The endoskeleton is an internal framework of bone and cartilage that provides support, protection, and attachment for muscles. It is found in vertebrates like humans, fish, and birds.