Kingdom Animalia Intro & Selected Phyla

Vocabulary flashcards covering key terms and concepts from the Animalia introduction, multicellularity, and detailed notes on flatworms and roundworms.

Animalia

Kingdom of multicellular, heterotrophic, eukaryotic organisms that ingest food internally.

Invertebrate

Animal lacking a backbone; makes up >97 % of animal species across 8 phyla.

Vertebrate

Animal with a backbone; all vertebrates belong to Phylum Chordata.

Eukaryote

Cell or organism whose cells possess a nucleus and membrane-bound organelles.

Heterotroph

Organism that cannot produce its own food and must obtain nutrients by ingestion.

Multicellularity

State of being composed of many cells, allowing larger size and cell specialization.

Surface-Area-to-Volume Ratio

Relationship influencing cell efficiency; higher ratios favor diffusion and metabolism in small cells.

Division of Labor

Specialization of cells into tissues/organs to perform different tasks efficiently in multicellular organisms.

Levels of Organization

Progression from cellular to tissue to organ and organ-system complexity in animals.

Asymmetrical Symmetry

Body plan with no plane of symmetry (e.g., sponges).

Radial Symmetry

Body parts arranged around a central axis; no true head (e.g., cnidarians).

Bilateral Symmetry

Body plan with mirror-image left and right sides, distinct head (anterior) and tail (posterior).

Cephalization

Concentration of sense organs and nerve cells at the anterior end of bilaterally symmetrical animals.

Ganglion (plural: Ganglia)

Cluster of nerve cells that can form primitive brains in complex animals.

Coelom

Fluid-filled body cavity completely lined by mesoderm, allowing organ specialization.

Acoelomate

Animal lacking a body cavity (e.g., flatworms).

Pseudocoelomate

Animal with a body cavity not fully lined by mesoderm (e.g., roundworms).

Coelomate

Animal whose coelom is entirely lined with mesoderm (e.g., annelids, vertebrates).

Diploblastic

Organism with two germ layers—ectoderm and endoderm (e.g., cnidarians).

Triploblastic

Organism with three germ layers—ectoderm, mesoderm, endoderm; usually bilaterally symmetrical.

Protostome

Developmental mode in which the mouth forms before the anus during gastrulation.

Platyhelminthes

Phylum of acoelomate flatworms exhibiting bilateral symmetry and cephalization.

Gastrovascular Cavity

Single-opening digestive cavity used for both ingestion and egestion in flatworms and cnidarians.

Flame Cell

Specialized excretory cell in flatworms that removes excess water and wastes.

Planaria

Free-living flatworm of Class Turbellaria capable of regeneration and asexual fission.

Trematoda

Class of parasitic flatworms (flukes) often requiring multiple hosts and having reduced systems.

Cestoda

Class of parasitic tapeworms lacking digestive and nervous systems but with extensive reproduction.

Monogenea

Class of ectoparasitic flatworms usually found on fish gills or skin, often host-specific.

Nematoda

Phylum of unsegmented roundworms with a pseudocoelom and complete digestive tract.

Pseudocoelom

Fluid-filled body cavity between mesoderm and endoderm found in nematodes.

Cuticle (Nematoda)

Tough, molted outer covering that protects roundworms and prevents desiccation.

Hydrostatic Skeleton

Support system using fluid pressure within a body cavity; utilized by nematodes for movement.

Whipworm

Parasitic nematode causing trichinosis in humans’ large intestine.

Hookworm

Blood-sucking nematode of small intestine causing anemia in dogs, cats, and humans.

Ascaris lumbricoides

Large intestinal nematode causing ascariasis; larvae migrate through lungs before maturing.

Ascariasis

Disease marked by abdominal pain and respiratory issues caused by Ascaris infection.

Filariasis

Nematode infection transmitted by mosquitoes leading to diseases like elephantiasis.

Elephantiasis

Severe limb/genital swelling from lymphatic blockage by filarial nematodes.

Free-Living Nematodes

Soil or aquatic roundworms acting as decomposers, recycling nutrients in ecosystems.

Ectoderm

Outer germ layer forming skin, nervous system, and external coverings.

Mesoderm

Middle germ layer forming muscles, bones, blood, and coelomic lining.

Endoderm

Inner germ layer forming gut lining, liver, and pancreas.

Gastrulation

Embryonic process forming germ layers and establishing the basic body plan.

Regeneration (Planaria)

Ability to regrow missing body parts after fission or injury.

Sessile

Describes organisms fixed in place, non-motile (common in radial animals).