Porifera and Cnidaria Flashcards
Body plan
AKA bauplan
The blueprint for the way the body of an organism is laid out
Major groups are distinguished by their unique body plan
Body plans differ in
Complexity of organization
Body symmetry
Developmental patterns
There are 32 different body plans in the animal phyla
Animal body plans differ in the grade of organization, in body symmetry, in the number of embryonic germ layers, and in the number of body cavities
Bilateral vs Radial symmetry
Bilateral - right and left sides (midsaggital division produces two mirror image halves)
Radial symmetry is where an object can be divided into equal halves by multiple planes
Phylum Porifera
Water enters body through pores, suspension feeders (they filter suspended particles from surrounding water)
How many species in Porifera?
Area they live?
Size?
Order?
15,000+
All aquatic, mostly marine
vary from a few mm to more than 2m
Cellular grade of organization
Extracellular matrix in a sponge is called…
Mesohyl
Sponges are _ symmetrical
Where do they live?
Asymmetrical or radial
They are sessile and attach to some sort of substrate, but the larva stage is free-swimming
They rely on ___ digestion
Sponges don’t gastrulate, so they have no gut and rely on purely intracellular digestion
Sponges pump water to obtain ___ and ___
Dermal ostia
Spongocoel
Osculum
oxygen and nutrients
Dermal ostia : incurrent pores
Spongocoel: Large internal cavity
Osculum : single large opening
Choanocytes do what? How do they accomplish this?
Pinocytosis?
Provide the force for driving water through the system
Beating of the flagellum draws water through the collar, where food is trapped on microvilli
Pinocytosis is the process of endocytosis done when the cell takes in fluid and dissolved small molecules, such as proteins
Pinacocytes
Phagocytize food particles at the sponge surface
Archaeocyte
Archaeocytes perform the intracellular digestion by pumping digestive enzymes into the food vacuole and extracting the nutrients, then ridding of the waste via exocytosis
Three types of sponge organization
Asconoid, simple
Syconoid, more complex
Leuconoid, most efficient and grows the largest
These do not define taxonomic groups
Sponge skeleton
Composed of…
Two types of spicules
Can be fibrous or rigid
Fibrous: Composed of collagen fibers in the extracellular matrix and spongin (a modified form of collagen in sponges)
Rigid: Composed of spicules, crystals that are either calcareous (CaCO3) or Siliceous (SiO2)
Three types of cells making spicules
Scleroblasts, calcoblasts, silicoblasts
Classification of sponges is based on…
Spicule form and Chemical composition
3 types, asconoid, syconoid, leuconoid
monoecious
Dioecious
Single sex in one organism
Two sexes in one organism
Phenotypic plasticity … makes classifying sponges hard
the ability of individual genotypes to produce different phenotypes when exposed to different environmental conditions
This is because the same genotype can be pressured differently and display morphologies different from its genetically identical neighbor
Harp sponge
Predacious sponge
Cnidaria
How many species?
90,000
Entirely aquatic, mostly marine
Cells are organized into tissues
Diploblastic
Radially symmetrical around a longitudinal axis
GV cavity (incomplete gut)
Tentacles
Nerve Net
Mouth end is…
Opposite end is…
oral
Aboral
Two germ lays give rise to…
Ectoderm and Endoderm give rise to epidermis, mesoglea, and gastrodermis
mesoglea is risen from some combination of ectoderm and endoderm
Gastrovascular cavity
Single opening that serves as mouth and anus
Serves in extracellular and intracellular digestion
Cnidocyte
Contain a nematocyst, which is concealed by an operculum
Describe cnidocyte mechanism
Are they reusable?
Operculum opens and the filament comes shooting out at high speed, turning inside out and exposes the barb with venom to a prey item
They are not reusable and become reabsorbed after use, then replaced with new ones
Cnidocytes are considered ___ predators
passive predators
Nerve Net
Very effective at?
Two interconnected nets, one with the epidermis, the other with the gastrodermis
3-D stimuli processing
Sensory cells do what?
They are meshed into the epithelial cells, and they are also interacting with the contractile cells that are extensions of epitheleum
Polyp vs. Medusa
Adapted to a sedentary or sessile life
Adapted for floating or free-swimming
Dimorphism
Two morphological types
Two types of polyps for Obelia need to know
Hydranths - feeding polyp
Gonangia - asexual reproductive polyp producing medusae
Define alternation of generations for Cnidarians
Polyps reproduce asexually to produce offspring that are medusa
Medusa reproduce sexually to form offspring that are polyps
Obelia forms what via?
Colonies
Budding - a type of asexual reproduction, where buds are genetically identical to its parent
What is obelia’s polyp like?
What is polymorphism?
Polymorphism - genetically identical individuals can develop into different groups of specialized individual polyps
Hydranth vs. Gonangia
Feeding bud vs. Reproductive Bud
Hydrozoa
Most are ___
Most are ___
Most ___
Most are marine
Most are colonial
Most exhibit alternation of generations with a poly stage that usually predominates with medusa small or sometimes absent
Hydrozoa skeleton…
resembling
What do they note have, and what is the consequence?
Form calcareous skeletons resembling pure coral
Hydrocoels in these do not have zooxanthellate algae, which means they can live in deeper waters
Hydrozoan medusae
Called
Possess what?
Are called hydromedusae
Possess a velum (therefore not a true jellyfish)
Hydra do not…
exhibit alternation of generations
–remain as polyps
—reproduce asexually or sexually depending on conditions (what does this mean?) and are capable of producing sexually
Budding is a form of…
Mitosis
Hydra two types
Monoecious (one type of egg or sperm)
Diecious (separate sexes)
Portuguese Man of war
A single is a colony of numerous polyps that specialize
Has 4 main types of polyps
-> one individual becomes the large gas filled bloat.
-> Other polyps become — tentacles, def/pray capturing tentacles
-> produce a potent neurotoxin
‘How long are man o war tentacles
165 feet
Schyphozoa
True jellyfishes with no velum and the medusa stage is typically large and free-living
Called a scyphomedusa
Polyp is small
Possesses cells in the mesoglea layer whereas hydras lack cells in the mesogleal layer
Aurelia have the same alternation of generations except for their sexual reproduction they don’t….
They don’t bud, rather they strobilate and form mini medusas
Anthozoa “flower animals”
Polyps are flower-like
No medusa stage
All marine
Solitary or colonial
Includes sea anemones, hard corals, soft and horny corals
Many forms support by skeletons
Anthozoa
GV cavity is large with partitioned septa (inward extensions of body wall)
GV cavity has gnidocytes with nematocysts
Some species of anthozoa can….
Swim if need be
Symbiotic relationship between clownfish and Amphiprion ocellaris
Clownfish has shelter and wards off prety
- The animal perhaps gets some recycled waste from the fish
- mucus on the fish’s skin prevents the anemones from firing
Anemones and symbiotic algae
What does algae get? fish get?
Sea anemones have algae growing within their gastrodermal cells
(zoochlorellae, zooxanthelle, or both)
Zooxanthelle receives shelter and N and P from host metabolism
Anemone receives nutrients (O2, etc) From the algae
Hard corals
Related to anemones
They are like mini-anemones that secrete calcareous cups that they inhabit
They are reef-building and have symbiotic relationships with zooxanthelle (algae)
Coral bleaching is the loss of zooxanthelle
Heat disrupts the metabolism of zooxanthelle, causing them to die or be expelled by the corals
Soft and horny corals
sea pens?
Includes gorgonians, sea fans, whip corals
Sea pens Are filter feeders that use colonies of polyps. These colonies use nematocysts to immobilize plankton and are filter feeders. Each gorgonian (sea fan) polyp has tentacles that catch plankton and particulate matter (filter feeding). Skeleton is made of flexible, horny substance named gorgonin
Describe the body plan of Porifera. (Be sure you understand what is meant by a “body plan” when constructing your answer)
The body plan of porifera is that that they are radially symmetrical or asymmetrical.
They have a spongocoel that acts as a body cavity.
They are of the multicellular level of organization.
Dermal ostia
Osculum
Members of the phylum Porifera have a very simple body structure, yet they are quite successful, with roughly 15,000 extant species. They possess no mouth, no gut, and they are sessile. How do they manage to capture and ingest food? Explain and be specific.
Choanocytes create flow of water by whipping their flagella around, and the food is trapped on the microvilli. The food is then trapped and phagocytized to be digested by archaeocytes, who will intracellularly digest the food with digestive enzymes unique to that cell. Pinacocytes phagocytize food particles at the body surface of the sponge. Choanocytes can phagocytize proteins by means of pinocytosis as well.
Gnidaria body plan
Radially symmetrical
Contain a gastrovascular cavity
Have an epidermis (with a nerve net), mesoglea, and a gastrodermis that are risen by an ectoderm and endoderm
They are the cell-tissue level of organization.
If adult Cnidaria possess three tissue layers, why are they referred to as diploblastic?
They are referred to as diploblastic because when they gastrulate, they only form an ectoderm and endoderm. Diplo refers to two and Blastic refers to germ layers - two germ layers.
Gastrovascular cavity
GV cavity is a gut that gives space for extracellular digestion to occur by placing digestive enzymes directly in the vicinity of food, and it also allows a place for intracellular digestion to occur because cells of the cavity can phagocytize food particles to be digested.
Cnidarians are able to capture and subdue prey items that are more intelligent and faster moving than they are. How do they manage to capture and ingest food? Explain and be specific.
They are passive predators that wait to be near their cnidocytes. Their cnidocytes shoot out nematocysts that can contain neurotoxins that subdue more intelligent organisms. The tentacles retract and pull the food item towards the gastrovascular cavity to be taken in and digested. It is a matter of patience.
With regard to cnidarians, what is meant by alternation of generations (= metagenesis)? Explain and give an example.
Alternation of generations in cnidarians means that there is an asexually reproducing polyp stage that can either bud or strobilate to produce offspring. These offspring become medusae and reproduce sexually, meaning there is a sperm fertilizing an egg which then become polyps, and the cycle continues in this fashion.
What is the difference between dimorphism and polymorphism as they apply to Cnidaria?
Dimorphism implies to there being two morphological types.
Polymorphism means genetically identical individuals can develop into different morphological types, (e.g. hydranths or gonangia)
How can you tell a hydrozoan medusa from a scyphozoan medusa?
Velum present and acellular mesoglea means hydrozoan medusa
True Jellyfish (scyphozoan) have no velum and a cellular mesoglea
What are some features that distinguish anthozoans from the other classes of Cnidaria?
Anthozoans look flower-like and do not have a medusa stage of life.
GV cavity has inward extensions of the body wall and is partitioned by septa.
GV cavity has cnidocytes with nematocysts inside it.
Hard corals are mini-anemones that secrete calcareous cups that they inhabit.
What is a colony, as this term pertains to cnidarians?
A colony of cnidarians is a cluster of cnidarians formed by budding new polyps. These polyps can take up a vast amount of space on the ocean floor and we call these coral reefs.
cnidocyte, nematocyst define/relate
Cnidocyte- The cell that is unique to cnidarians, which house their tool of hunting prey
Nematocyst - a barbed organelle of the cnidocyte that is propelled out of the cnidocyte when it senses prey nearby, sometimes containing neurotoxins
Cnidocytes utilize nematocysts to incapacitate prey so the tentacles of the cnidarian can draw the food item into the gastrovascular cavity without it putting up much of a fight.
Choanocyte vs Archaeocyte define/relate
Choanocyte - A cell in the sponge that is responsible for creating flow through the sponge so that food items can be caught on the microvilli of the cell.
Archaeocyte - responsible for intracellular digestion, whereby it phagocytizes food particles brought in by pinacocytes or choanocytes and releases digestive enzymes onto the food to create usable energy for the sponge.
1 alternation of generations
2 choanocytes
3 cnidocytes
4 diploblastic
5 gastrovascular cavity
6 nematocysts
7 nerve net
8 sessile adults
9 spicules
10 suspension feeders
1.) Cnidaria
2.) Porifera
3.) Cnidaria
4.) Cnidaria
5.) Cnidaria
6.) Cnidaria
7.) Cnidaria
8.) Porifera
9.) Porifera
10.) Porifera
