lecture 1

Vocabulary practice flashcards covering fundamental taxonomy, metazoan evolutionary innovations, phylogenetic debates, feeding modes, and physiological adaptations of intertidal marine invertebrates from BIO237 lecture notes.

Invertebrates

Animals lacking a vertebral column, representing approximately 97% of all animal diversity and numbering over 1,000,000 described species compared to fewer than 6,000 vertebrate species.

Animal-mediated fertilization in seaweed

A marine reproductive interaction (documented by Lavaut et al., 2022) in which invertebrate isopods transfer non-motile male gametes (spermatia) to female reproductive structures in red algae, acting as underwater pollinators.

Eumetazoa

A major clade of multicellular animals characterized by the evolution of true differentiated tissues, distinguishing them from the tissue-lacking Parazoa (sponges).

Bilateria

A major animal group distinguished by bilateral symmetry, triploblastic tissue organization, and cephalization, contrasting with the radially symmetrical Radiata.

Protostomia

A major lineage of bilateral animals defined by protostome developmental characteristics, where the embryonic blastopore typically forms the mouth first.

Deuterostomia

A major bilateral clade (including echinoderms and chordates) defined by deuterostome embryonic development (where the blastopore becomes the anus) and the presence of an endoskeleton.

Lophotrochozoa

A clade of protostome animals characterized by either the presence of a specialized feeding structure called a lophophore or a free-swimming ciliated trochophore larval stage.

Ecdysozoa

A clade of protostome animals (including nematodes and arthropods) defined by ecdysis, the evolutionary trait of periodically shedding a non-living cuticle or exoskeleton.

Ctenophora-sister hypothesis

The phylogenetic hypothesis proposing that comb jellies (Ctenophora), rather than sponges (Porifera), represent the earliest-diverging sister group to all other animals, implying complex nervous systems and muscles either evolved independently or were subsequently lost in Porifera and Placozoa.

Nekton

Free-swimming pelagic animals within the water column capable of active locomotion and navigating independently of ambient water currents.

Plankton

Organisms suspended within the water column that lack sufficient swimming ability to propel themselves against water currents.

Holoplankton

Organisms that remain planktonic throughout their entire life cycle.

Meroplankton

Organisms that spend only a temporary portion of their life cycle—typically the larval or egg stage—as plankton before transitioning to benthic or nektonic lifestyles.

Filter feeder

An aquatic animal that feeds by extracting suspended food particles and microorganisms directly from the surrounding water using specialized filtering structures.

Deposit feeder

An aquatic animal that obtains nourishment by consuming sediment and digesting the associated organic matter, detritus, and microorganisms.

Intertidal zone

The marine coastal habitat situated between the highest high-tide and lowest low-tide water marks, cyclically exposed to air during low tide and submerged during high tide.

Subtidal zone

The marine littoral habitat situated below the lowest low-water spring tide level, remaining continuously submerged.

Ectothermic

Relying primarily on external environmental heat sources rather than metabolic processes to regulate body temperature.

Poikilothermic

Having an internal body temperature that fluctuates in accordance with variations in the ambient temperature.

Eurythermal

Capable of tolerating and functioning across a broad range of environmental temperatures.

Euryhaline

Capable of surviving and adapting to wide variations in ambient salinity levels.

Hypoxia

A condition of deficient dissolved oxygen ($O_2$), which frequently develops in intertidal rockpools at night when algal and animal respiration depletes oxygen, or during high-temperature summer conditions.

Hypercapnia

An elevated concentration and partial pressure of carbon dioxide ($CO_2$) within an aquatic environment, driven by organismal respiration exceeding photosynthetic uptake.

Intertidal vertical zonation

The banded distribution of organisms along the shore gradient, where the upper shore limit is typically determined by physical environmental tolerances (desiccation, temperature) and the lower shore limit is governed by biological interactions (competition, predation).

$$LT_{50}$$

The median lethal temperature at which 50% mortality occurs in an experimental group, used to quantify and compare whole-organism thermal tolerance between species.