Photo Credit: Photograph by Chris Newbert/Minden Pictures Aquatic Life – Invertebrate Animals In this unit we will introduce characteristics of aquatic organisms and focus on invertebrate animals (that lack a backbone).

Characteristics of Animals All animals are eukaryotic; their cells have a nucleus and specialized organelles. Their cells DO NOT have cell walls, differentiating them from bacterial and plant cells. All animals are multicellular. Because animals cannot make their own food they are considered heterotrophs.

Essential Functions Homeostasis Feeding/Excretion Support/Movement Respiration/ Circulation Response to Environment Reproduction s/schools-fish/school-of-grunt-fish-photography.html

Homeostasis Homeostasis is the process by which animals maintain a fairly stable internal environment. Organisms require a set of constants for survival. Aquatic organisms must stabilize (homeostasis) their body temperature, oceanic species must adapt to saline environments, etc.

Feeding and Excretion Animals must find, consume, and digest food for energy. They must also get rid of waste products. Just as the machines in a factory produce waste, the cells of organisms often produce a “trash” substance called ammonia which is poisonous. The excretion (to get rid of) of wastes from the body varies between organisms. creatures/pygmy-seahorse-doubilet.html

Most animals are active and require energy for movement. Some animals are sessile, or permanently attached to one spot (EX sponges). Most animals are motile and are free-moving at some time in their life cycle (which allows offspring to settle in a new place). Some animals are passive and move only when carried by another force such as water currents or wind. erwater-scenes/basket-sea-star-photography.html Support & Movement

Respiration & Circulation Animals must have oxygen to release energy within cells. Some animals use lungs while some aquatic animals use gills to bring in oxygen and get rid of the CO2 by product of cellular activity. Others use diffusion to pass the gases in and out of their body.

Response Animals must be aware of their environment to obtain food, seek protection from predators, find mates and reproduce, etc. Animals respond to their environment using specialized nerve cells to sense external stimuli (light, sound, etc) and to process information. EX The shark using senses. graphy/photo-of-the-day/shark-kingman-reef- pod.html

Reproduction Animals must reproduce to maintain the species. Most reproduce sexually using sperm and an egg. Some can reproduce asexually (from just one parent).

Animal Body Symmetry Radial symmetry – arrangement of body parts around a central point (EX starfish). Bilateral symmetry – arrangement of body parts along a plane (EX heart, centipede). Asymmetry – lack of symmetry (EX sponge). mmetry_comparison.gif

Invertebrates vs. Vertebrates The animal kingdom is divided into two main groups: Invertebrates – without backbones Vertebrates – with backbones

Phylum Porifera Sponges are the oldest and simplest and probably most unusual animals, classified in the Phylum Porifera.  Name means “pore- bearer” and are often seen in their dried form as natural sponges used for bathing.

Sponge Characteristics Sponges are sessile organisms that do not move (as adults). No symmetry (asymmetry) Sponges lack special tissues and organs. They have special structures that allow water to pump through their body which help the sponge to respire and filter food and excrete waste. Sponge Video

Phylum Cnidaria Think floating jellyfish and sea anemones (home to Nemo)! Found in water all over the world, Phylum Cnidaria (C is silent) are soft bodied, carnivorous animals that have stinging tentacles. Cnidarians link

Cnidarians Characteristics orhiza_shawi.JPG

Cnidarians Cont. Cnidocytes – unique cells that contain stinging, poisonous barbs that are used to capture prey found on their tentacles. The display radial symmetry. Reproduce sexually or asexually (1 way) by budding Cnidarians make up the world’s coral reefs and float along with currents. Stunning Jelly (Search jellyfish) Stunning Jelly es/Underwater-Realm-2.jpg

Cnidarians Examples gequest3d.com /photos/combje llies/index.htm Cnidarian Video

Phylum Platyhelminthes – Flatworms Flatworms are classified as part of the Phylum Platyhelminthes. Flatworms are un- segmented (no rings) and appear flat, most no more than a few millimeters thick. They have tissues and internal organs systems, bilateral symmetry, and cephalization (which means they have a head!) Flatworm video

Flatworm Characteristics They have a single digestive opening, a Mouth/Anus in which food enters and undigested waste leaves. Because they are so thin, most flatworms do not need a circulatory system to transport materials, but use diffusion. Respiration also occurs through diffusion.

Flatworms Cont. They move to obtain food and escape predators. They can be both carnivorous or parasitic (this tapeworm lives inside the human intestines). elminthes/tapeworms.jpg

Phylum Nematoda/Nemertea – Roundworms Also known as roundworms, Phylum Nematoda consists of unsegmented worms that can be microscopic or a large as a meter in length! Most roundworms are free living and are found in the soil, the sea floor, or water. Others are parasites that live in plants and animals. orm_90p_P jpg

Phylum Annelida – Segmented Think earthworms and leeches! Phylum Annelida consists of the common earthworm and is characterized by worms with segmented bodies. The name means “little rings”. Worm Video

Phylum Mollusca Think snails, clams, and the octopus! Mollusks are characterized by soft bodies that is sometimes protected by a hard shell. glossary/mollusk.jpg

Mollusks Cont.

Classes of Mollusks Kingdom Animalia / Phylum Mollusca / Class… Class Polyplacophora (Chitons – most primitive mollusks) Class Gastropoda (mollusks with shells; EX snails) Class Bivalva (mollusks with a hinged shell; EX clams and oysters) Class Cephalopoda (advanced, intelligent mollusks; EX nautilus, squid, octopus, cuttlefish which have a closed circulatory system) chart.com/dig _photo/clams.JPG com/3_kids/20_ca mouflage/images/o ctupus.jpg

Phylum Echinodermata Think starfish (sea stars), sand dollars, and sea urchins! Phylum Echinodermata means "spiny skin“ and these organisms live only in the ocean. Echinoderms have the ability to regenerate their limbs.

Echinoderms Cont. These are the elaborate filter-feeding tentacles of a Sea Apple.

Echinoderms Cont. Kingdom Animalia / Phylum Echinodermata / Class… Class Asteroidea – sea stars or starfish Class Ophiuroidea – brittle stars and basket stars Class Echinoidea – sea urchins and sand dollars Class Holothuroidea – sea cucumbers Class Crinoidea – sea lilies and feather stars

Phylum Arthropoda The butterfly, the spider, and the shrimp all belong into the Phylum Arthropoda, which means “jointed feet”. Characterized by bilateral symmetry, they have segmented bodies fused into larger body regions. Arthropod Video umb/9/99/150px-Zorak-Mantis.png

Arthropod Characteristics Their jointed feet are specialized for sensing, eating, reproducing, moving and defending. Arthropods have a complex digestive system with two openings and a closed circulatory system (blood vessels like us). Exoskeleton - made of chitin; is a hard covering on the outside of body which provides both support and protection Molting – required for an arthropod to grow; shedding of old exoskeleton

Arthropoda Subphylum: Crustaceans Think crawfish, lobsters, and crabs! Crustaceans have legs with claws, chewing mouthparts, two pair of antennae, and two body segments. 4/shrimp.jpg