phylum cnidarian pt 2

What are four common examples of animals belonging to Phylum Cnidaria?

Sea fans ("soft coral"), jellyfish, coral, and sea anemones

Where do cnidarians split from the animal lineage relative to sponges on the phylogenetic tree?

They are the next split from the animal lineage right after sponges

What does the term "Eumetazoa" mean?

True animal

What are three distinct evolutionary changes that characterize Eumetazoans?

Two embryonic cell layers (diploblastic), distinct organ systems, and true tissues

What are the main characteristics of the cnidarian lifestyle?

Simple carnivores, predators, very low metabolic rates, and the ability to survive in cold, nutrient-poor waters

What is an example of an Antarctic jellyfish mentioned in the lecture?

Desmonema glaciale

What are the four major taxonomic groups/classes of cnidarians?

Scyphozoans, Hydrozoans, Cubazoans, and Anthozoans

What are the two general body plan forms exhibited by cnidarians?

Polyp and Medusa

What type of basic symmetry do cnidarians possess?

Radial symmetry

What are the two layers of living tissue in a cnidarian's body wall?

Epidermis (outer layer) and gastrodermis (inner layer)

What is the middle gelatinous layer located between the two living tissue layers called?

Mesoglea

What anatomical structure surrounds the mouth of a cnidarian?

Tentacles

What is a "blind gut" in reference to cnidarians?

A digestive system with only a single opening that serves as both the mouth and the anus

What are the three main purposes of the gastrovascular cavity?

Digestion, gas exchange, and circulation

How do cnidarians perform gas exchange and circulation without specialized organs?

Through a diffusion-based system within the gastrovascular cavity

What type of digestion occurs in the gastrovascular cavity using enzymes from the gastroderm?

Extracellular digestion

What are the specialized stinging cells unique to Phylum Cnidaria called?

Cnidocytes

What is a synapomorphy?

A feature or characteristic that every species in a Phylum shares

What is the name of the organelle/capsule ejected by a cnidocyte to sting prey?

Nematocyst (literally meaning "threadbags")

What are the three types of cnidocytes found in cnidarians and their functions?

Spirocysts (entangle prey), Ptychocysts (shoot adhesive threads), and Nematocysts (shoot a stinging thread with toxin)

What triggers the discharge of a nematocyst?

A structural "trigger" on the cnidocyte that causes the coiled thread to discharge into the cuticle of prey

What are the defining characteristics of Scyphozoans?

The "true jellyfish," possessing a thick mesoglea, large and effective swimmers, all marine, and classified as gelatinous zooplankton

What is an example of a massive, dangerous Scyphozoan mentioned in the slides?

Lion's mane jellyfish

What unique ecological group is found within the Hydrozoans?

The only freshwater cnidarians, alongside marine forms

What is the Portuguese man-of-war (Physalia physalis) classified as?

A siphonophore (a type of hydrozoan)

What are the four specialized types of individuals (zooids) that make up a Portuguese man-of-war colony?

Pneumatophore (the sail), Dactylozooid (defense/fishing), Gastrozooid (feeding), and Gonozooid (reproduction)

What hydrozoan species is known as the "By-the-wind Sailor" and causes mass beach strandings in California?

Velella velella

What are the characteristics of Cubazoans?

Box jellies, small but highly toxic, all marine, and includes the sea wasp (Chironex fleckeri)

What does the name "Anthozoans" mean in Greek?

Flower animals

What types of organisms belong to the Anthozoan clade?

Corals and sea anemones

What does it mean that almost all corals are colonial organisms?

They are composed of hundreds to hundreds of thousands of individual animals called polyps

What is the genus name of the photosynthetic algae that live mutualistically inside coral tissues?

Zooxanthellae (also referred to as Symbiodinium)

Describe the mutualistic relationship in a coral-algal symbiosis.

The coral receives nutrition from the algae's photosynthesis, while the algae receive a protected environment and compounds needed for photosynthesis

What is coral bleaching?

The loss of symbiotic zooxanthellae and/or a reduction in photosynthetic pigments due to high-temperature stress

What components make up the diverse coral symbiotic ecosystem/microbiome?

Polyps, Symbiodinium, prokaryotes, viruses, and a surface mucus layer

Name three environmental variables that can cause a responsive change in the coral microbiome.

Temperature increase, nutrients increase, pH decrease, and dissolved organic carbon loading

What percentage of all marine life depends on coral reefs?

25%

How many people worldwide depend on coral reefs for food, income, and coastal protection?

1 billion people

What is the estimated economic value of services provided by global coral reefs each year?

$375 billion

What conservation approach is being researched by Ruth Gates and Madeleine van Oppen to build coral reef resilience?

Human-assisted evolution

What biological processes are leveraged in human-assisted evolution for corals?

Intra-generational acclimatization, transgenerational acclimatization, and genetic selection/adaptation

What are two scalable reef restoration practices mentioned at the end of the lecture?

Coral farming and promoting genetic diversity