Chapter 33: Pt 1. An Introduction To Invertebrates Flashcards
(42 cards)
Invertebrates are animals that lack a back bone. They account for ___% of known animal species.
95%
_________ are basal animals that lack true tissues.
Sponges
Define sessile
Fixed in one place, immobile.
Sponges have organized cells supported by a skeleton made of 3 different things. What are they?
- Spongin fibers
- Calcareous spicules
- Silica spicules
Or sometimes, no skeletal structure at all.
How do sponges eat?
They are suspension/filter feeders.
- choanocytes create a current that draws water in through the sponge’s pores into the spongocoal and out of the osculum
- food particles from the water get trapped in the mucus that coats the projections
- food is transferred to amoebocytes
How do sponges break down the food particles?
Phagocytosis
In some reef systems, sponges are __________ feeders - taking in enough biomass to double every 2-3 days.
voracious
organisms who devour great quantities of food
Sponges have a chamber called an _______, which consists of many spongocoel and choanocytes.
atrium
What is the mesophyl?
The center layer of a sponge, between the outer and inner layer of cells.
Both the outer and inner layer of a sponge’s wall have contact with water. What does this mean?
Gas exchange and waste removal can occur by diffusion across the cell membranes of both the inner and outer wall.
What are amoebocytes?
Cells that move through the mesophyl. They take up absorbed food and carry nutrients to other cells.
Sponges have three body types. What are they and what are their differences?
- Asconoid
- smallest, simplest body design.
- looks kind of like a tear drop.
- Syconoid
- middle sized, somewhat complex design.
- looks like the tear drop, but has flagellated canals along the sides.
- Leuconoid
- largest, most complex design.
- looks like a typical sponge with many oscula.
How do sponges contribute to the antibiotics we have today?
There are many bacteria that live within the sponges that help with antibiotics.
Sponges are refuges
What does this mean?
They provide habitats for a wide variety of animals
What phylum do sponges belong to?
Phylum Porifera
Define eumetazoa
Clade of the animal kingdom that includes all multicellular animals except sponges
What is gastrovascular cavity?
Cavity in the body that digests food and transports nutrients throughout the body
- only has one opening, mouth and anus are the same
What are cnidarians?
A phylum of animals belonging to the clade eumetazoa
- jellyfish, anemonies etc.
What are characteristics of cnidarians?
- Two body types
> sessile polyps
> motile medusas - Simple diploblastic, radial body plans
- Central digestive compartment (gastrovascular cavity)
- Mouth and anus are same opening
What is the body plan of a cnidarian?
Sad with a central digestive compartment (gastrovascular cavity)
What is a polyp?
A sessile cnidarian that adheres to substrates.
- they extend their tentacles to catch prey
E.g., sea anemone and hydras
What is a medusa?
A motile cnidarian that swims freely.
- their tentacles face downward for locomotion
E.g., jellyfish
What are the 3 layers of a cnidarian’s wall?
Epidermis
Mesoglea (gel-like)
Gastrodermis
What is a unique trait to cnidarian tentacles?
They are composed of cnidocytes
- cnidocytes are cells that consist of specialized organelles called nematocysts that eject a stinging thread to catch prey
