Lecture 12 Flashcards
Explain what a reef is, and what the conditions are that favor reef formation.
Reef: organic sedimentary buildup with a framework
formed by an animal with a hard skeleton. they prefer warm water, sunlight, clear water, and stable conditions
How is sponge organization different from that of other animals? In particular, what function to choanocytes have?
They lack organs and tissues like muscles or nerves.
Choanocytes create currents in the water, bringing in food particles. Their job is to catch these particles on their collars and eat them, sort of like how a filter catches dirt from water.
What kind of symmetry do sponges, cnidarians, and most bilaterians have?
Sponges: They don’t have a specific shape and can look quite irregular. They don’t have a clear left or right side.
Cnidarians (like jellyfish and corals): They’re shaped like a circle or a tube, with body parts arranged around a central point. Imagine a pizza sliced into equal pieces.
Most Bilaterians (like humans, dogs, and birds): They have a clear left and right side that mirror each other, just like how your face looks similar on both sides. Think of folding a piece of paper in half; both sides look the same.
What are ways that sponges reproduce? What is a gemmule?
sponges reproduce through budding, fragmentation, and sexual reproduction
gemmule is like a tiny survival pd helping sponges survive (archaeocytes)
Know the differences between hexatinellids, calcarea, desmosponges, and stromotoporoids.
Hexactinellids (Glass Sponges): These sponges have skeletons made of silica, which gives them a glassy appearance. They have six-pointed spicules (tiny skeletal structures) arranged in a lattice-like pattern.
Calcarea (Calcium Sponges): These sponges have skeletons made of calcium carbonate, similar to what shells are made of. They usually have simple body structures and their spicules are typically small and have different shapes.
Desmosponges (Diverse Sponges): Desmosponges are the largest and most diverse group of sponges. They have skeletons made of a flexible protein called spongin or a combination of spongin and silica or calcium carbonate. They can be found in various shapes and sizes.
Stromatoporoids (Extinct Sponges): Stromatoporoids are ancient sponges that lived millions of years ago. They had skeletons made of calcium carbonate and often formed massive structures resembling mounds or reefs. They are no longer found alive today.
What were the first major reef formers, and when did they live?
stromatolites is not true reef formers but are considered to be the first because it is the oldest known evidence of microorganisms. old atleast 3.5 billion years ago during archean eon.
early cambrian is when first reef forms archeaocyathan reefs.
What is the basic organization of a cnidarian body? What is the difference between a medusa and a polyp?
A cnidarian’s body is like a sac. It has two layers of cells: an outer layer called the epidermis and an inner layer called the gastrodermis. In between these layers is a jelly-like substance called mesoglea. Cnidarians also have a central mouth surrounded by tentacles armed with stinging cells called cnidocytes.
Medusa: A medusa is like a jellyfish. It’s bell-shaped and floats in the water. Its mouth is on the underside, and it has tentacles that dangle down.
Polyp: A polyp is like a tiny tube stuck to the seafloor or attached to something solid. It has a mouth on top surrounded by tentacles, kind of like an upside-down jellyfish. don’t move around much.
How does alternation of generations work in cnidarians that have both the
medusa and polyp stages?
the alternation of generations in cnidarians involves switching between the polyp stage, where reproduction is asexual and stationary, and the medusa stage, where reproduction is sexual and free-swimming.
When are tabulate and rugose corals most abundant? Know the difference between favositids and halysitids.
tabulate and rugose corals were most abundant during the paleozoic era and helped build big reefs
Favositids: These corals looked like honeycombs with small holes. They lived in colonies and made reefs from the Ordovician to the Permian periods.
Halysitids: These corals had long, tube-like structures that linked together like a chain. They also lived in colonies and made reefs from the Ordovician to the Devonian periods.
What is a hermatypic coral?
A hermatypic coral is a type of coral that builds reefs. These corals have a special relationship with algae called zooxanthellae, which live inside their tissues and help them get food from sunlight through photosynthesis. Hermatypic corals are important for building and maintaining coral reefs in tropical oceans around the world.
Know the basic history of reef formers! Specifically:
a. Archaeocyanthans in the Cambrian
b. Tabulate and rugose corals and stromatoporoids in
the Ordovician, Silurian, and Devonian
c. Glass sponges (Hydnoderas) in the late Devonian. d. Calcareous sponges and algae in the Permian
e. Scleractinian corals in the Triassic to today, except
for…
f. Rudistid bivalves in the Cretaceous
a. Archaeocyanthans (Cambrian): These were ancient organisms related to modern corals. They were some of the earliest reef builders, appearing in the Cambrian period over 500 million years ago.
b. Tabulate and Rugose Corals, and Stromatoporoids (Ordovician, Silurian, and Devonian): These were major reef builders during the Paleozoic Era. They formed extensive coral reefs in shallow seas, contributing to the diversity of marine life during this time.
c. Glass Sponges (Late Devonian): These sponges had skeletons made of silica, giving them a glassy appearance. They were present in the late Devonian period, adding to the diversity of reef builders during this time.
d. Calcareous Sponges and Algae (Permian): During the Permian period, calcareous sponges and algae contributed to reef formation. They added to the structure and diversity of ancient reefs.
e. Scleractinian Corals (Triassic to Today): Scleractinian corals, also known as hard corals, have been the primary reef builders since the Triassic period and continue to be important today. They form the framework of modern coral reefs in tropical oceans.
f. Rudistid Bivalves (Cretaceous): During the Cretaceous period, rudistid bivalves were significant reef builders. They were bivalve mollusks with unusual cone-shaped shells and formed large reefs in shallow seas, especially in the Tethys Ocean.
