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Flashcards: BIO 121a list 1
Common Ancestry
All organisms share a universal common ancestor.
Evolution
Change in populations over time due to genetic variation and natural selection.
Natural Selection (VISTA)
Variation, Inheritance, Selection, Time, and Adaptation drive evolutionary changes.
Adaptive Radiation
Diversification from a common ancestor to exploit various ecological niches.
Cambrian Explosion
A period of rapid diversification of multicellular life approximately 540 million years ago.
Radial Symmetry
Body parts arranged around a central axis, common in cnidarians.
Bilateral Symmetry
Body plan with two symmetrical halves, characteristic of Bilateria.
Triploblastic
Three germ layers: ectoderm, mesoderm, and endoderm.
Protostome
Animals where the mouth develops from the blastopore.
Deuterostome
Animals where the anus develops from the blastopore.
Ostia
Small pores on a sponge's body through which water enters.
Choanocytes
Collar cells in sponges responsible for water flow and capturing food.
Spicules
Structural elements made of calcium carbonate or silica in sponges.
Ascon, Sycon, Leucon
Three basic body plans of sponges.
Cnidocytes
Specialized stinging cells unique to cnidarians.
Nematocysts
Organelles within cnidocytes that deliver a sting to capture prey.
Medusa
Free-swimming, umbrella-shaped body form of cnidarians.
Polyp
Sessile, cylindrical body form of cnidarians.
Metamerism
Segmentation of the body into repeated units.
Clitellum
Thickened, glandular section of annelids used for reproduction.
Parapodia
Paired lateral appendages in polychaetes for locomotion and gas exchange.
Setae
Bristle-like structures on annelids used for anchorage and movement.
Water Vascular System
Network of hydraulic canals used in locomotion, feeding, and respiration.
Mutable Collagen
Tissue in echinoderms that can rapidly change stiffness.
Pedicellaria
Pincer-like appendages in echinoderms for cleaning and defense.
Aristotle’s Lantern
Chewing apparatus in sea urchins used for scraping food.
Notochord
A flexible rod that provides support in chordates.
Dorsal Hollow Nerve Cord
Tube-like structure above the notochord; develops into the central nervous system.
Pharyngeal Slits
Openings in the pharynx used for filter-feeding or respiration.
Endostyle/Thyroid
Structure involved in iodine metabolism; precursor to the thyroid gland.
Placoid Scales
Tooth-like scales in cartilaginous fishes.
Lateral Line System
Sensory system in fishes that detects water vibrations.
Ampullae of Lorenzini
Electroreceptive organs in cartilaginous fishes for detecting electrical fields.
Heterocercal Tail
A tail with unequal lobes; provides lift in sharks.
Pulmo-cutaneous Respiration
Gas exchange through lungs and moist skin in amphibians.
Amplexus
Reproductive clasping behavior in frogs.
Paedomorphosis
Retention of juvenile traits into adulthood, seen in some salamanders.
Double Circulation
A circulatory system with separate pulmonary and systemic circuits.
Feathers
Modified scales used for flight, insulation, and display.
Contour Feathers
Streamline the body for flight.
Precocial
Chicks born well-developed and able to feed themselves.
Altricial
Chicks born underdeveloped and requiring parental care.