Chaonoflagellates, Sponges, Cnidarians, Ctenophores

9/21 + 9/23 Lecture (Bio 302)

Chaonoflagellates 

Free-living, aquatic eukaryotes that are the closest living relatives of animals (metazoa). They are found in both marine and freshwater environments and exist as either single-celled organisms or colonies. Their study provides key insights into the evolution of multicellularity in animals.

Porifera

a phylum of simple, multicellular aquatic animals that lack true tissues, organs, and symmetry, characterized by a porous body used to filter food and oxygen from water (sponges).

Pinacocytes

flat, epithelial-like cells that form the protective outer layer, or pinacoderm, of sponges

Spicules

small, needle-like, mineral or organic structures found in various organisms, most notably in the skeletons of sea sponges to give them shape

Chaonocytes

specialized cells in sponges that have a single, whip-like flagellum surrounded by a collar of microvilli. Their main functions are to generate water currents for feeding and respiration by pumping water through the sponge, and to trap food particles like bacteria and plankton for digestion.

Osculum

a large aperture in a sponge through which water is expelled

Ostia

the numerous, tiny openings on a sponge's exterior that allow water to enter its body, which is crucial for feeding, respiration, and excretion

Sclerocytes

specialized cells in certain invertebrates, particularly sponges, that secrete spicules, which are mineralized skeletal elements providing structural support and protection to the organism

Spongocoel

the large, central, water-filled cavity within a sponge's body where water enters through numerous small pores (ostia) and exits through a single larger opening, the osculum

Porocytes

specialized, tubular cells in sponges that form the ostia, or pores, through which water enters the sponge's body

Amoebocytes

transport nutrients and expel of waste throughout a sponges body. These cells have the ability to differentiate into other specialized cells.

Totipotent

the most versatile type of stem cell, capable of differentiating into any cell type in the body

Mesophyl

the gelatinous, collagen-rich matrix between the inner and outer cell layers, providing structural support and housing various cells for nutrient transport and reproduction

Spongin

the horny or fibrous substance found in the skeleton of many sponges

Canal systems

consists of pores (ostia), canals, flagellated chambers with choanocytes (collar cells), and oscula, which are responsible for water circulation to facilitate food intake, gas exchange (respiration), waste removal (excretion), and reproduction

Filter Feeding

feeding by filtering out plankton or nutrients suspended in the water

Regeneration

the ability of sponges to repair damaged tissue or regrow an entire body from a small piece or even from dissociated cells

Budding

a form of asexual reproduction where a new, genetically identical sponge grows as an outgrowth from the parent sponge's body

Gemmule

tough-coated dormant cluster of embryonic cells produced by a freshwater sponge for development in more favorable conditions

Porifera Sexual Reproduction

involves the release of sperm and eggs into the water, which then fertilize to form a zygote that develops into a free-swimming larval stage

Class: Calcarea

Spicules are made of Calcium Carbonate (CaCO3) are viviparous

Viviparous

the embryo develops inside the parent's body, and the parent then releases live larvae into the water

Class Demospongiae

Largest class of sponges: >80% of
sponge species. Lack CaCO3 in their skeleton. Contain all species of freshwater sponges.

Class Hexactinellida

“glass sponges” are characterized by skeletons made from four- and/or six-pointed siliceous spicules. They are mostly found in deep, cold waters but can also form large reefs. These sponges are know for living for a very long time (15,000 years)

Cnidarians

contain soft-bodied stinging animals such as corals, sea anemones, and jellyfish

Medusa

a free-swimming, typically umbrella-shaped body form that hangs downwards with tentacles

Polyp

the sessile body form of a cnidarian, such as a coral or sea anemone, characterized by a cylindrical body with a mouth and tentacles at the top and attached to a surface at the bottom

Dimorphic

contain both body forms (medusa and polyp) at some point in their life cycle

Cnidocytes and Nematocyst 

Cnidocytes are specialized stinging cells in cnidarians that contain nematocysts, which are harpoon-like organelles that discharge a coiled, barbed thread to capture prey or defend against predators

Planula Larvae

he free-swimming, ciliated larval stage of many cnidarians that develops after fertilization and before settling to the ocean floor to become a polyp

Nerve Net

the simplest form of a nervous system consisting of a decentralized, interconnected mesh of nerve cells that allow impulses to spread in multiple directions, enabling a coordinated but undirected response to environmental stimuli

Gastrovascular Cavity

a central organ in some simpler animals, such as cnidarians and flatworms, that functions for both digestion and circulation of nutrients and gases

Class Scyphozoa

“True Jellyfish” Named for their thick,
gelatinous layer of non-living
material between tissue layers:
Mesoglea

Rhopalia

Sensory organs that detect light and gravity to control orientation and swimming

Class Cubozoa

“Box Jellyfish” are characterized by their complex eyes and fatal nematocysts. Found primarily in the pacific.

Class Hydrozoa

Polyp phase dominates life cycle. Medusae are much smaller than ‘true’ jellies. Contain orders Hydroida and Siphonophora.

Class Anthozoa

Largest class of cnidarians (6000 species) in which all species are marine and polypoid

Polypoid

the sessile, cylindrical form of cnidarians, characterized by a body stalk attached to a substrate, with a mouth and tentacles facing upward (contain sea anemones and coral)

Phylum Ctenophora

a group of marine invertebrates known for their gelatinous, translucent bodies, biradial symmetry, and unique locomotion using eight rows of ciliated "comb plates"

Comb Rows

eight longitudinal bands of fused, comb-like cilia that function as a primary means of locomotion

Colloblasts

unique, mushroom-shaped, adhesive cells that secrete a sticky substance to capture prey

Biradial

a rare form of animal symmetry that combines characteristics of both radial and bilateral symmetry

Anal Pores

a specialized opening, found in some single-celled organisms and simple multicellular animals, through which waste products are expelled from the body

Hermaphrodite

a biologically an organism that produces both male and female gametes

Selective Breeding

a human-driven process that involves choosing specific plants or animals with desirable traits to reproduce together, with the goal of producing offspring with more pronounced or enhanced versions of those traits

Foundation Species

organisms that play a critical role in shaping their ecosystem by creating and maintaining habitat, providing food, and influencing the overall community structure (ex. coral reefs)

Bleaching Event

when ocean heat stress causes corals to expel the symbiotic algae that provide them with food and color, leaving them white and vulnerable to death

Corals of Opporitunity

naturally detached coral fragments or colonies that become dislodged from a reef due to storms, boat groundings, or other disturbances that scientist use to study heat tolerance in coral