Protostomes Lecture Notes

Flashcards reviewing key vocabulary and concepts from the Protostomes lecture.

Protostome

A bilaterian lineage where the mouth develops before the anus in the embryo.

Importance of Protostomes

Live in almost every habitat and play ecological roles such as decomposers, herbivores, and carnivores.

Schistosomiasis

Schistosomes cause this disease, affecting ~200 million people worldwide through contact with contaminated freshwater.

Intestinal parasite causing ascaris infection

Ascaris lumbricoides

Spread filarial worms, causing lymphatic filariasis (elephantiasis).

Mosquitoes

Protostomes that moved to land

Examples include earthworms and arthropods.

Lophotrochozoa

Includes mollusks, flatworms, and segmented worms, growing incrementally.

Ecdysozoa

Includes arthropods and roundworms, growing by molting.

Flatworms (Phylum Platyhelminthes)

Flat bodies and no circulatory or respiratory systems. Must live in moist environments due to dependence on surface diffusion

Major groups of Flatworms

Turbellaria, Cestoda, Trematoda, Monogenea

Cestoda (Tapeworms)

Internal parasites in vertebrates absorbing nutrients across the body surface.

Annelids (Segmented Worms)

Complete digestive tract and segmented body.

Three Major Groups of Annelids

Polychaeta, Oligochaeta, Hirudinea

Polychaeta

Mostly marine worms with parapodia and chaetae.

Oligochaeta (Earthworms)

Mostly terrestrial or freshwater worms that ingest soil and extract nutrients.

Hirudinea (Leeches)

Attach to fish, humans, or other animals to suck blood or body fluids.

Medical use of Leeches (Hirudotherapy)

Restore blood flow in delicate surgical areas and relieve venous congestion.

Key Body Parts of Mollusks

Foot, visceral mass, and mantle.

Visceral Mass (Mollusks)

Contains organs and gills; the coelom is reduced and organs sit in a hemocoel.

Mantle (Mollusks)

Secretes the shell, forms a lung (snails), forms siphons (bivalves), and a siphon for jet propulsion (cephalopods).

Four Major Groups of Mollusks

Chitons, Bivalves, Gastropods, Cephalopods

Ecdysozoa

Protostomes that grow by molting, shedding a cuticle or exoskeleton.

Ecdysone

A hormone that regulates the molting cycle.

Phylum Nematoda - Roundworms

Unsegmented worms with a pseudocoelom and elastic cuticle.

Ascaris lumbricoides (Ascariasis)

Contaminated food or soil, causing stomach pain, malnutrition, blockage of intestines.

Hookworms (Ancylostoma, Necator)

Bare feet (from soil), feeding on blood from the intestinal wall, causing fatigue, anemia, and weakness.

Filarial Worms

spread by mosquito bites and live in the lymphatic system causing elephantiasis

Molting (Ecdysozoans)

Shedding of the soft cuticle or hard exoskeleton.

Tardigrades ("Water Bears")

Microscopic, slow-moving animals found in moss, soil, and water films.

Arthropods

Most diverse animal group with a segmented body, exoskeleton, and jointed appendages.

Arthropod Body Plan

Segmented body, exoskeleton, and jointed appendages.

Three Main Features of Arthropods

Tagmata (e.g., head, thorax, abdomen), exoskeleton (chitin), jointed appendages.

Why Arthropods Are Successful

Segments can evolve into specialized tools; tool-kit genes allow body variation.

Four Major Arthropod Lineages

Myriapods, Insects, Crustaceans, Chelicerates

Insects - Body Plan

A arthropod group with compound eyes, antennae, mouthparts on the head, 3 pairs of legs and often wings on the thorax, and digestion/reproduction in abdomen.

Insect Adaptations

First animals to evolve powered flight and undergo metamorphosis.

Crustaceans

Head, thorax, and abdomen; two pairs of antennae; branched appendages.

Chelicerates

Cephalothorax and abdomen; no antennae; chelicerae and pedipalps.

Incomplete Metamorphosis

Juveniles look like small adults.

Complete Metamorphosis

Distinct larval stage → pupa → adult.