Some Happy Sea Creatures By Margaret Barnett Mary Jacobs Hanuel Jo

Porifera (a.k.a Sponges) – No symmetry (asymmetrical) – Body is multicellular Number of germ layers and coelom: Cells and tissues surround a water filled space – is no true body cavity. -2 germ layers: endoderm and ectoderm

More Porifera Type of body development: -The larvae – flagellated – swim freely for a short time After settling down and attaching to the ground, the larvae develop into young sponges. -All are sessile (live attached to something).

Porifera instead of mouths, they have tiny pores in their outer walls through which water flows. have few tissues but no organs and a nervous system Did you know? – Until 1765, sponges were thought to be plants because they were so simple. – Chemicals from sponges are being used to find a cure for cancer and other diseases

Porifera Reproduction: sexually or asexually – Asexual reproduction occurs by budding or by fragmentation. buds may remain attached to the parent or separate from it each bud develops into a new individual. Most sponges are hermaphroditic, the same individual produces both eggs and sperm – in some species the sexes are separate.

Specialized tissues of Porifera Throughout the body of sponges, there are canals through which water flows. The canals have openings to the outside, where the water enters the sponge. – These usually small pores are called ostia – the pores are larger where the water leaves the sponge system These pores are called oscula(singular osculum). – These canals are mostly lined with special flagellated cells called choanocytes. Choanocytes filter small food items from the water such as individual bacteria. skeletal elements called spicules: the cells that support the body

Cnidarians Radial Symmetry Movement is coordinated by a decentralized nerve net and simple receptors – If they are free swimming they have more complex nervous systems For example eyes, a gravity sensing organ, and an inner ear similar to the ones in vertebrates Have a sac-like body in two distinct layers

Cnidarians Continued Gastro Vascular cavity- functions in both digestion and gas exchange Two forms: – Polyp: cylindrical, sessile, the mouth is facing upward, does asexual reproduction – Medusa: umbrella shaped, free swimming, mouth facing downward, does sexual reproduction

Cnidarians The tentacles contain cnidocytes that are cells which contain needle-like organelles called cnidae Nematocysts are cnidae stinging capsules – Found on the end of the tentacles of cnidarians

Ctenophores (a.k.a.comb-jellies) Ctenophore means “comb-bearer” similar in appearance to cnidarian medusi about 100 different species 1-10 cm in diameter Most are spherical or ovoid (egg shaped) Each ctenophore has eight rows of comb-like plates composed of fused cilia the largest animals to use cilia for locomotion

Portuguese Man-of-War Colony Not a jellyfish, it is a siphonophore Each man-of-war is composed of four types separate polyps – One polyp makes up the gas filled structure called the pneumatophore. When inflated, the pneumatophore resembles a Portuguese battleship floating on the surface of the water. The chamber can be deflated to allow the organism to submerge. – The second polyp makes up the tentacles. Tentacles are an average of 30 feet long but can grow to a length of 165 feet. The tentacles contain nematocytes that sting and help capture prey. – The third type of polyp, gastrozooids, surround the food and digests it.

Coral Reef Formation Coral reefs are composed of colonies of living coral organisms and limestone skeletons of dead coral Reefs occur only in clear tropical saltwater (64 degrees) at shallow depths that allow for penetration of sunlight Coral depends on a symbiotic relationship with the zooxanthellae, an algae that grows in coral tissue