Comprehensive Coverage of Key Invertebrate Phyla and Evolution

Flashcards generated from lecture notes on cellular organization, protozoans, sponges, cnidarians, nematodes, and flatworms for exam preparation.

What are lobopodia?

Large, blunt extensions used for locomotion and feeding.

What are filopodia?

Thin, sharp extensions containing only ectoplasm.

What are reticulopodia?

Branching and rejoining extensions that form a net-like mesh.

What do phagotrophs or holozoic feeders in protozoans do?

Ingest visible particles by engulfing them via infolding of the cell membrane.

What do osmotrophs or saprozoic feeders in protozoans do?

Absorb soluble food across their cell membrane.

What are cilia?

Short, hair-like structures that propel water parallel to the cell surface.

What are flagella?

Longer, whip-like structures that propel water parallel to the flagellum axis.

What are pseudopodia?

Temporary extensions of the cell body used for movement and feeding.

What happens during binary fission, the most common type of asexual reproduction in protozoans?

Equal halves are produced.

What happens during budding?

Small progeny cell pinches off from the parent cell.

What occurs during multiple fission or schizogony?

Multiple nuclear divisions precede cytokinesis, resulting in many daughter cells.

What is the function of the endoplasm in pseudopodia movement?

Contains the nucleus and organelles.

What is the ectoplasm?

More rigid, clear outer layer of cytoplasm.

What is the nucleus?

Membrane-bound organelle containing DNA.

What is the function of the macronucleus in ciliates?

Controls metabolic and developmental functions in ciliates.

What is the function of the micronuclei in ciliates?

Functions in sexual reproduction in ciliates.

What is the function of the mitochondria?

Is responsible for energy recovery.

What is the function of the Golgi apparatus?

Secretory and digestive functions.

What is the function of plastids?

Contain photosynthetic pigments, like chloroplasts.

What are extrusomes?

Membrane-bound organelles used to extrude material, such as trichocysts for defense in ciliates.

What happens in sexual reproduction?

Involves gametes (sex cells).

What are isogametes?

Gametes that look alike.

What are anisogametes?

Gametes that are dissimilar.

What occurs during conjugation?

Exchange of genetic material, as seen in Paramecium.

What happens during autogamy?

Self-fertilization without gamete exchange, as seen in Paramecium.

What is the Subphylum Euglenida (Euglena) characterized by?

Photosynthetic with chloroplasts.

What is the Subphylum Kinetoplasta (Zooflagellates) characterized by?

Includes Trypanosoma, which causes sleeping sickness and Chagas disease.

What are cysts?

Dormant, resistant forms that survive harsh conditions.

What is characteristic of Phyla Retortamonada and Diplomonads (e.g., Giardia)?

Lacks mitochondria and Golgi bodies.

What is characteristic of Parabasalids?

Includes Trichomonas vaginalis, which causes urogenital tract infection.

What is characteristic of Heterolobosea?

Life cycle includes amebic and flagellated stages; Naegleria fowleri causes amoebic meningitis.

What is characteristic of Phylum Euglenozoa?

Longitudinal microtubules.

What does Clade Opisthokonta include?

Includes Metazoan animals, fungi, and some unicellular taxa (e.g., choanoflagellates).

What unites Clade Alveolata?

United by the presence of alveoli (flattened vesicles beneath the cell membrane).

What is unique about Phylum Ciliophora (Ciliates)?

Have two nuclei: macronucleus (metabolic) and micronucleus (reproductive).

What covers Ciliates?

Covered by pellicle and numerous cilia.

What is the role of cytostome (mouth) in ciliates?

Leads to cytopharynx.

What are trichocysts and toxicysts used for?

Used for defense/prey capture.

What is Phylum Dinoflagellata (Dinoflagellates) characterized by?

About half are photoautotrophic, have two flagella, and may be bioluminescent.

What are zooxanthellae?

Mutualistic symbionts with corals, essential for coral reef formation.

What is unique about Phylum Apicomplexa?

All are intracellular parasites.

What does Elmeria and Isospora cause?

Causes coccidiosis in fowl/humans.

What is Toxoplasma gondii?

Parasite of cats; infects humans via undercooked meat; dangerous during pregnancy.

What is Malaria (Plasmodium)?

Four species infect humans (e.g., P. vivax, P. falciparum), transmitted by Anopheles mosquitoes and involves human liver cells and red blood cells.

What are foraminifera?

Shelled amoebas with calcium carbonate tests and slender pseudopodia extending through openings.

What are radiolarian?

Marine, pelagic, with intricate silica skeletons and axopodia.

What are Amoebozoa?

Amoebas with flattened mitochondrial cristae.

What does Amoeba castellani cause?

Causes corneal infections.

What does Entamoeba histolytica cause?

Causes amebic dysentery; invades intestinal wall.

What has molecular phylogeny led to?

Has led to the concept of eukaryotic supergroups (e.g., Plantae, Rhizaria, Excavates, Opisthokonta).

What are sponges or poriferans?

Simplest multicellular animals, characterized by their filter-feeding system and cellular-level organization.

What is the function of choanocytes (collar cells)?

Create water currents and capture food (0.1–50 μm).

What is characteristic of Porifera (pore-bearing) bodies?

Incurrent dermal ostia and excurrent oscula.

What is the mesohyl?

Gelatinous extracellular matrix containing cells and skeletal elements.

What are pinacocytes?

Flat, epithelial-like cells forming the outer pinacoderm.

What is the role of choanocytes in sponges?

Create water current, trap food, and pass it to archaeocytes.

What is the role of sclerocytes in sponges?

Secrete spicules.

What is the role of spongocytes in sponges?

Secrete spongin.

What is the role of collencytes/lophocytes in sponges?

Secrete collagen.

What are gemmules in asexual reproduction?

Internal buds of archaeocytes coated with spongin/spicules, resistant to harsh conditions.

What are asconoids?

Simplest, small, tube-shaped; choanocytes line the large central cavity (spongocoel).

What are syconoids?

Larger, thicker body wall with choanocyte-lined radial canals emptying into the spongocoel.

What are leuconoids?

Most complex and largest, with clusters of flagellated chambers.

What is somatic embryogenesis?

Regeneration of whole organisms from fragments.

What are calcarea?

Calcareous sponges with calcium carbonate spicules (straight, 3- or 4-rayed).

What are hexactinellida (glass sponges)?

Six-rayed siliceous spicules; mostly deep-sea.

What are demospongiae?

95% of living species; siliceous spicules (not 6-rayed) or spongin fibers; all are leuconoid.

What are placozoa?

Trichoplax adhaerens is a single species phylum, extremely simple with no symmetry, muscular, or nervous organs, and three cell layers.

What are cnidarians?

Possess cnidocytes, containing nematocysts (stinging organelles) for prey capture and defense; mostly marine; radial or biradial symmetry; diploblastic.

What is a polyp (hydroid form)?

Sessile, tubular, mouth and tentacles usually upward; attaches by a pedal disc.

What is a medusa?

Free-swimming, bell- or umbrella-shaped, mouth downward, tentacles from rim; equipped with statocysts (balance) and ocelli (photosensitivity).

What are the 2 germ layers of a diploblastic animal?

Outer epidermis, inner gastrodermis.

What is the incomplete gut of cnidarians?

Gastrovascular cavity serves as mouth and anus, for extracellular and intracellular digestion.

What is the musculature of cnidarians?

Epitheliomuscular cells with longitudinal and circular fibers.

What is nematocyst discharge?

Rapid, explosive discharge due to water rushing into capsule. Barbs inject poison.

What are hydrozoa?

colonial, and exhibit both polyp and medusa stages.

What are siphonophora?

Polymorphic swimming/floating colonies (e.g., Physalia - Portuguese man-of-war).

What are scyphozoa (true jellyfish)?

Medusa stage is dominant and often large. Lack a velum. Bell margins have lappets and sensory rhopalia.

What are cubozoa (box jellyfish)?

Medusa is cube-shaped with tentacles from each corner; known for potent venom.

What are anthozoa (sea anemones and corals)?

Exclusively polyp form; lack a medusa stage; all marine, found in deep and shallow waters; gastrovascular cavity is large and partitioned by septa.

What are hexacorallia (zoantharia)?

Hexamerous symmetry. Includes sea anemones and true/stony corals (Scleractinia).

What are hexalian corals?

Miniature sea anemones living in calcareous cups they secrete

What are alcyonaria (octocorallia)?

Octomerous symmetry

What are staurozoa (stalked jellyfish)?

Solitary polyp with a stalk, resembles a medusa at the top (8 extensions with tentacles); no true medusa stage; attached to substrates.

What are nematodes?

Cylindrical shape; covered by a tough, flexible, non-living cuticle; pseudocoelom.

What is a pseudocoelom?

Fluid-filled body cavity that acts as a hydrostatic skeleton.

What is the musculature of nematodes?

Body wall contains only longitudinal muscles, leading to a characteristic thrashing movement.

What are the habitats of nematodes?

Found in virtually all habitats (soil, marine, freshwater). Free-living forms are decomposers or predators.

What is the digestive system of nematodes?

Complete digestive system: mouth, muscular pharynx, non-muscular intestine, short rectum, anus.

What is the nervous system of nematodes?

Ring of nerve tissue around the pharynx, leading to dorsal and ventral nerve cords.

What is Ascaris lumbricoides?

Common human intestinal parasite; infection from ingesting contaminated soil/food.

What is Trichinella spiralis?

Causes trichinosis; adults burrow in intestinal mucosa, females produce live juveniles; juveniles encyst in skeletal muscle cells.

What are pinworms (Enterobius vermicularis)?

Most common helminthic parasite in the US; adults live in large intestine; females migrate to anal region at night to lay eggs, causing itching.

What are filarial worms (e.g., Wucheria bancrofti, Brugia malayi)?

Live in the lymphatic system; cause inflammation and blockage, leading to elephantiasis; transmitted by mosquitoes.

What are hookworms (e.g., Necator americanus)?

Small worms with hook-like anterior end; cut into intestinal mucosa and suck host's blood, causing anemia.

What are nematomorpha (horsehair worms)?

Sister taxon to nematodes; adults free-living in moist habitats, juveniles are arthropod parasites

What are flatworms (platyhelminthes)?

Flat bodies (dorsoventrally flattened); bilateral symmetry; acoelomate.

What does acoelomate mean?

Lack a true coelom; space between body wall and organs filled with parenchyma cells.

Why is it correct to say that because parasitic flatwoms don't possess a ciliated epidermis, that they are made up of subphylum Neodermata?

Subphylum Neodermata, characterized by a non-ciliated, syncytial outer covering called a syncytial tegument or neodermis, which protects them from host enzymes because parasitic worms don't have ciliated epidermis, as the free-living worms do.

What is the digestive system of flatworms?

Incomplete digestive system with a single opening (mouth), a muscular pharynx, and a blind-ended intestine (no anus).