Unit 4 - Invertebrates PDF

 CONTENTS 01 02 03 THE ANIMAL KINGDOM PORIFERA CNIDARIANS 04 05 06 WORMS MOLLUSCS ARTHROPODS 07 ECHINODERMS “If we and the rest of the b...

 CONTENTS 01 02 03 THE ANIMAL KINGDOM PORIFERA CNIDARIANS 04 05 06 WORMS MOLLUSCS ARTHROPODS 07 ECHINODERMS “If we and the rest of the back- boned animals were to disappear overnight, the rest of the world would get on pretty well. But if the invertebrates were to disappear, the world's ecosystems would collapse.” - David Attenborough 1.1 Characteristics of animals All animals share certain characteristics: They have limited growth. The majority move from one place to another. Most of them have bilateral symmetry, but others have radial symmetry, and few are asymmetrical. They have a high level of interaction. Animals form complex structures (tissues, organs…) 1.1 Characteristics of animals All animals share certain characteristics: They have respiratory organs adapted to their environment. They have sexual reproduction, but some invertebrates can have asexual too. They can have external fertilisation or internal fertilisation. Development can be direct or indirect (metamorphosis). DIRECT DEVELOPMENT INDIRECT DEVELOPMENT 1.2 Classification of animals 1.200.000 species Is the stimated number of animal species on our planet 96 % 4% The great majority are Only a small percentage invertebrates corresponds to vertebrates  1.3 Characteristics of Invertebrates Between a sponge and a crab there are many differences, but all invertebrates share 2 main characteristics: They do not have a backbone.. They are ectotherms → their temperature is dependent on the temperature outside their bodies.  2. Phylum Porifera Porifera are aquatic sessile animals that mainly live on the sea. They have radial symmetry or are asymmetrical. They don’t have tissues. Their body is sac shaped covered with pores. CREDITS: This presentation template was created by Slidesgo, including icons by Flaticon, and infographics & images by Freepik.  2. Phylum Porifera They have an internal skeleton composed of: Rigid spines → Spicules Flexible fibres → Spongin Porifera feed by a filtration process. Choanocytes create a stream of water to obtain nutrients and oxygen from the water. They perform sexualtemplate CREDITS: This presentation reproduction was and created by Slidesgo, including icons by asexual reproduction (Fragmentation). Flaticon, and infographics & images by Freepik. Porifera filtrating 3. PHYLUM CNIDARIANS Cnidarians are aquatic animals that have radial symmetry. Their cells are grouped in simple tissues. There are 2 groups of Cnidarians: ○ Polyps: Sac-shaped sessile cnidarians. They can have an external or internal skeleton. ○ Jellyfish: Umbrela-shaped. They have a hidrostatic skeleton (made of water). 3. PHYLUM CNIDARIANS They have a digestive cavity and tentacles. Cnidoblasts: stinging cells that can paralyse the prey. They are carnivores. They perform sexual reproduction and asexual reproduction (budding), but some species perform alternating reproduction. How cnidoblasts work? →  Cnidoblasts in action 4. Worms The term “worms” is not a taxonomic category, but it is used to refer to 3 different phyla: Flatworms, Nematodes and Annelids. All of them have bilateral symmetry. They live in humid climates. They don’t have jointed appendages 4. Worms 4.1 FLATWORMS (Phylum Platyhelminthes) They are the simplest bilateral animals with cephalization → concentration of nerves centres in the front part of the organism (they have head). There are 2 groups of Flatworms: Tapeworms: parasites that live in the intestines of many animals (including humans). Planarians: free-living aquatic organisms. 4. Worms 4.2 NEMATODES (Phylum Nematoda) Nematodes are worms with unsegmented cylindrical bodies. Some of them are parasites and others are free- living. They have a mouth and an anus. They perform sexual reproduction. 4. Worms 4.3 ANNELIDS (Phylum Annelida) Annelids are worms with segmented cylindrical bodies that are divided into segments called metameres. They can be aquatic or live in humid terrestrial environments. They have a digestive tube (mouth→anus). They can breathe through gills or carry out subcutaneous respiration (through the skin). They perform sexual reproduction.  5. Phylum Mollusca 5.1. Characteristics: Molluscs are invertebrates with soft body and bilateral symmetry. The majority are aquatic (with some exceptions). Many molluscs have a hard shell, that can be internal or external. They have a head and they move using a muscular foot. If they are aquatic, they have gills, if they are terrestrial, they have lungs.  5. Phylum Mollusca Molluscs can be classified into 3 groups: 5.1. Bivalves (Bivalvia): ○ Aquatic molluscs that have 2 external shells or valves. ○ They are filter feeders. ○ They breathe through gills. ○ They don’t have a head.  5. Phylum Mollusca 5.2. Gastropods (Gastropoda): ○ Mainly aquatic molluscs that have an external spiral-shaped shell (Some don’t). ○ Some of them can be terrestrial (slugs/snails). ○ They have a head with 4 tentacles. ○ They are herbivores. ○ They have a heart with an open circulatory system.  5. Phylum Mollusca 5.3. Cephalopods (Cephalopoda): ○ Aquatic molluscs that have an internal shell (except for octopi). ○ Their foot is near their head and its’s divided into tentacles with suction cups. ○ They have a well defined head with prominent eyes. ○ They have a beak-shaped jaw. ○ They have a closed circulatory system.  Clam digging into sand Gastropods shells  Cuttlefish camouflage Octopus intelligence  6. Phylum Arthropoda Arthropods are the most varied and largest phylum of the animal kingdom. More than 75% of all known species belong to this group. Characteristics: They have bilateral symmetry. Their bodies are protected by an exoskeleton made of chitin. In order to grow, they perform moulting.  6. Phylum Arthropoda They have segmented bodies and articulated appendages. Aquatic arthropods breathe through gills, whereas terrestrial use tracheas (conducts) or lungs. They have a well developed nervous system and sense organs. They perform sexual reproduction and they undergo a process called metamorphosis to transform into adults.  6. Phylum Arthropoda Arthropods are classified into 4 groups: 6.1 MYRIAPODS Myriapods are terrestrial arthropods that have a pair of antennae on their heads and bodies divided into segments. There are 2 groups: Chilopoda: (centipedes) usually flat with 1 pair of legs per segment → Carnivorous. Diplopoda: (millipedes) cylindrical bodies with 2 pairs of legs per segment → Herbivores.  6. Phylum Arthropoda 6.2 ARACHNIDS (Arachnida) Arachnids are terrestrial arthropods. Their bodies are divided in 2 parts: the cephalothorax and the abdomen. They have four pairs of legs and don’t have antennae. They have special appendages called chelicerae There are 3 groups: Spiders: produce a viscous liquid (Spider’s web). Scorpions: Segmented abdomen with a sting. Mites: Fused cephalothorax with abdomen.  6. Phylum Arthropoda 6.3 CRUSTACEANS (Crustacea) Their bodies are divided into a cephalothorax and an abdomen. They have two pairs of antennae and five pairs of legs on their cephalothorax. The majority of crustaceans are aquatic. They have mobile eyes. They have non-articulated appendages in their abdomen.  6. Phylum Arthropoda 6.4 INSECTS (Insecta) Arthropods that have a head, thorax and abdomen. They have a pair of antennae on their head and three pairs of legs on their thorax. Insects have one or two pairs of wings. The majority of them live on land. They have compound eyes and a variety of mouthparts. They undergo metamorphosis, that can be complete or incomplete.  INCOMPLETE COMPLETE In incomplete metamorphosis, a nymph hatches from the egg and has to shed its skin several times in order to be adult In complete metamorphosis, larvae hatches from the egg and enters into chrysalis state to reach adulthood  Chilopoda in nature Spider building its web  Hermit crabs fighting for a shell Insect biodiversity 7. PHYLUM ECHINODERMATA Echinoderms are aquatic invertebrates that live in the sea. They generally have radial symmetry. They have a dermoskeleton, consisting of rigid plates under the skin. They move using an ambulacral system, a network of tubes through which water circulates → movement. They have a complete digestive system. They perform sexual reproduction, and some can reproduce by fragmentation (asexual reproduction). 7. PHYLUM ECHINODERMATA There are 3 groups of echinoderms: 7.1 Echinoids (Echinoidea): Echinoids, or sea urchins, are echinoderms that have globular bodies with fused plates that form a shell, and long spikes which they use to defend themselves. They are herbivores / saprophytes. 7. PHYLUM ECHINODERMATA 7.2 Asteroideans (Asteroidea): Asteroideans, or starfish, have disc-shaped bodies with arms. They usually have five arms, although some species have more than ten. They are carnivores.  7. PHYLUM ECHINODERMATA 7.3 Holothurians (Holothuroidea): Holothurians, or sea cucumbers, have long bodies with no arms or spikes. They are detritivores (saprophytes). STARFISH WALKING SEA URCHIN DEVELOPMENT MEDIA: Giant Jellyfish Giant clam swimming Invertebrate groups Nematod Insect Sunflower parasite adaptations starfish hunting