Exploring Creation with Marine Biology Module 4 - Marine Invertebrates I

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kingdom Animalia

the largest kingdom (highest number of species)

the two subgroups of kingdom Animalia

invertebrates and vertebrates

invertebrates

animals that do not possess a backbone

vertebrates

animals that possess a backbone

phylum Porifera

sponges; a group of organisms composed of complex groups of specialized cells that do not work together like true tissues, but cluster into special groups organized into a recognizable organism

substrate

a bottom surface sponges tend to attach to

why is the sponge group called Porifera

they create pores (it means pore-bearing)

pore cells

tube-like cells that allow water to move into the animal

collar cells

cells inside the canals of a sponge’s body with flagellum that create water currents flowing into the sponge; the cells have a collar surrounding the flagellum that traps food particles

osculum

a large opening on a sponge through which filtered water is expelled

laterally

from the sides

apically

from the top

where does water enter a sponge

enters laterally

where does water exit a sponge

exits apically

three basic sponge body types

asconoid, syconoid, and leuconoid

asconoid

has a canal type like a sack filled with holes

syconoid

similar to asconoid but has slight folds in the sides for more surface area

leuconoid

similar to syconoid, but with even more folds for even greater surface area

spicules

made of calcium carbonate or silica and make up a skeletal support frame for larger, more complex sponges

aggregation

when a broken sponge’s pieces can come back together and reorganize

spongin

elastic protein fibers that make up a web-like skeleton to provide support; more flexible than spicules

amoebocytes

cells within a sponge that produce its skeletal structure, perform digestion, and repair cell damage

budding

a type of asexual reproduction in sponges in which an individual develops a small outgrowth on its body, pinches off, and eventually matures into a new sponge

in what ways can a sponge reproduce

sexually and asexually (regeneration, budding, and gemmules)

gemmules

a group of cells surrounded by a shell of spicules that can endure long periods of harsh weather and opens when conditions are suitable again, releasing the cells inside to grow

parenchymula

planktonic sponge larvae that are released into water and float with the currents until they settle to mature

larva

an immature stage of an animal that appears different from the adult stage

metamorphosis

a complete morphological change from larva to adult

morphological

referring to the form and structure of an organism

phylum Cnidaria (coelenterates)

organisms containing a coel; has specialized tissues and have the ability to move in an intricate way

coel

large body cavity

three kinds of symmetry

spherical, radial, and bilateral

spherical symmetry

a body form in which any cut through the organism’s center would result in identical halves

radial symmetry

a body form in which any longitudinal cut through the organism’s central axis would result in identical halves

bilateral symmetry

a body form in which only one longitudinal cut through the organism’s center would result in identical halves

aboral side

opposite the mouth

oral side

side with a mouth

polyp

an attached cnidarian stage, appearing sac- or barrel-like

medusa

a free-swimming cnidarian stage, appearing bell- or umbrella-like

traits shared by polyps and medusas

a centrally located mouth surrounded by tentacles, nematocysts, gastrovascular cavity, and a jelly-like body layer

nematocysts

unique stinging structures located at the ends of tentacles that can paralyze prey or ward off predators

gastrovascular cavity

a cavity inside a cnidarian’s body where food is digested; not a true gut (only has one opening)

mesoglea

a jelly-like substance between the inner layer and outer layer of cells in a cnidarian

what two layers surround the mesoglea

ectoderm (epidermis) and endoderm (gastrodermis)

carnivores

organisms that prey on other organisms

most cnidarians are (referring to diet)

carnivorous

planula

the free-swimming larval stage of a medusa

how do medusas reproduce

produce eggs and sperm that result in a planula that matures into either a medusa or a polyp (sexually)

how do polyps reproduce

1) budding, 2) releasing medusae, 3) producing gametes to create a larva that turns into either a polyp or a medusa

nerve cells

specialized cells that make up a simple nervous system, allowing cnidarians to identify each other and coordinate their body movements for water movement

three classes of Cnidarians

hydrozoans, scyphozoans, and anthozoans

class Hydrozoa

~3000 species, possessing various types of body structures and life cycles, form colonies of tiny polyps; sometimes forms special floating colonies of polyps on a special medusa

class Scyphozoa

~300 species, including larger jellyfish; possess rounded medusa body, allowing for movement; some have specialized nerve cells that can detect light for orientation in water

class Anthozoa (corals and sea anemones)

~6000 species, the largest group of cnidarians; either solitary or colonial organisms, spending their entire life cycle as polyps; gastrovascular cavities are lined with septa for digestion

septa

vertical partitions that line the gastrovascular cavity in anthozoans to allow for greater surface area for digestion

zooxanthellae

special symbiotic dinoflagellates that produce carbohydrates by photosynthesis and share with corals

anthozoans that form branching or elongated skeletons

sea fans, sea plumes, and black corals

anthozoans that form colonies without hard skeletons

soft corals and sea pens

anthozoans that are muscular polyps existing as solitary individuals or colonies

sea anemones

phylum Ctenophora (comb jellies)

a smaller group of radially symmetrical, gelatinous-bodied, small planktonic marine organisms that use 2 long tentacles covered in lasso cells to capture prey

lasso cells

special cells that burst and release sticky threads to capture prey

ctenes

ciliary combs located vertically along the bodies of comb jellies that beat along the length of a comb jelly’s body for propulsion

dorsal

referring to the top or back surface of an animal

ventral

referring to the bottom or belly surface of an animal

phylum Platyhelminthes (flatworms)

bilaterally symmetrical, flattened organisms with the simplest organization of organs and organ systems among all bilaterally symmetrical animals; have a simple brain (a collection of nerves in the head) and a simple central nervous system, an intestine, and a special middle layer of tissue that forms muscles and contributes to other organs during development

central nervous system

coordinates the movements of a flatworm’s muscles

intestine

a baglike structure that digests food and expels waste

turbellarians

a group of free-swimming, carnivorous, colorful flatworms that move with the help of cilia and mucus on the ventral side to move along the ocean bottom

mutualism

a relationship between two or more organisms of different species where both benefit from the association

commensalism

a relationship between two or more organisms of different species where one benefits and the other is neither harmed nor benefited

parasitism

a relationship between two or more organisms of different species where one benefits and the other is harmed

class Trematoda (flukes)

the largest group of flatworms; basically flukes

flukes

parasitic flatworms that feed on the tissues of other organisms

how do flukes spread

as larvae they infect smaller invertebrates such as clams, then mature into adults inside of vertebrates that consume the invertebrates

host

the organism housing a parasite

class Cestoda (tapeworms)

long-bodied parasites that live in the intestines of both land and aquatic vertebrates, attaching to the walls with suckers or hook structures; do not have a gut or mouth, so they rely on the host to digest food for them

phylum Nemertea (ribbon worms)

mostly marine flat, ribbon-shaped worms that live along the ocean floor; possesses a one-way digestive system (true digestive system) and a proboscis for defense and capturing prey

proboscis

a long, tubular structure used for defense or capturing prey

phylum Nematoda (roundworms)

mostly parasitic worms that typically reside in fish or in ocean sediment, feeding on bacteria and organic matter; possess small, slender, tube-like bodies tapered on both ends and a true digestive tract

phylum Annelida (segmented worms)

worms that exhibit segmentation, possess a coelom, and have a distinct circulatory system

segmentation

when an organism’s body has a design made up of a series of similar compartments (segments)

coelom

a body cavity within organisms containing specialized tissue

class Polychaeta (polychaetes)

the most diverse and abundant class of annelids that have parapodia along each of their body segments; larger ones possess gills for oxygen absorption

gills

extensions of the body containing thin-walled blood vessels that allow for easy absorption of oxygen from the outside surface; found in larger polychaetes

how do marine polychaetes reproduce

sexually, by releasing gametes into the water column to yield trochophores that metamorphose into adult polychaetes

trochophores

free-swimming larvae of polychaetes

Lophophorates

special bilaterally symmetrical organisms with lophophores, making them suspension feeders; possesses a coelom and a U-shaped gut rather than a straight one

lophophore

a crown of ciliated tentacles around the mouth used for gathering food

phylum Bryozoa (moss animals)

mostly marine organisms that form colonies of interconnected individuals, sometimes resulting in a crusty, lace-like form; lophophores surround the mouth and can retract

phylum Phoronida

organisms that resemble polychaete worms and build tubes made of sand grains, but have a U-shaped gut; most burrow in sand or attach to hard surfaces in shallow water

phylum Brachiopoda (lamp shells)

special marine oragnisms that look like clams but have shells on the dorsal and ventral parts of bodies rather than the left and right sides; possess ciliated lophophores between the shells for gathering food